Graham Jones of timeanddate.com joins with Deborah Byrd of EarthSky to explain why the December 4-5 quarter moon – aka a ‘half moon’ – is more than 50% illuminated. Plus, we share some key moon dates for 2024, from the closest moon to the shortest lunar month. Original article from timeanddate.com on November 27, 2023. Reprinted with permission. Edits by EarthSky.

Quarter moon or half moon?

From our perspective on Earth, the 3rd quarter moon on the night of December 4-5, 2023, will be the most-illuminated quarter moon of this year. It’ll be 50.137% lit, as seen by us on Earth.

A quarter moon looks half-illuminated in Earth’s sky. Some people even call it a half moon. And we in astronomy often say a quarter moon – aka a half moon – appears from Earth to be 50% illuminated.

But it’s not true. Instead, every quarter moon (half moon) is always slightly more than 50% illuminated.

And the December 4-5, 2023, quarter moon is the most illuminated of all the quarter moons this year.

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A fraction more than half?

Who knew that a quarter moon is always more than half illuminated? That’s not common knowledge, even among astronomers. But it’s true.

Here’s why. In astronomy, we define the instant of quarter moon as when the sun and moon are separated by 90 degrees, as seen from Earth.

But, in order for the moon to appear exactly 50% illuminated for an observer on Earth, the sun and Earth must be separated by 90 degrees, from the perspective of the moon.

See? It’s a tiny difference, but a measurable one. From Earth, at every quarter moon, a fraction more than 50% of the Earth-facing side of the moon is illuminated.

Not to scale

The illustration above is a very rough representation of the triangle formed by the sun, Earth, and moon. In reality, the distance from Earth to the moon is about 30 times the diameter of Earth. The distance from Earth to the sun, meanwhile, is around 12,000 times Earth’s diameter.

In other words, although our not-to-scale illustration shows a small and compact triangle, the actual triangle is extremely long and narrow.

As the moon travels along its orbit, the moment when it is exactly 50% illuminated comes around 20 minutes after the moment of 3rd quarter, or before the moment of 1st quarter.

(Our illustration ignores an effect called parallax, where the moon’s position differs by a tiny amount depending on your observing location on Earth. Moon phase calculations are based on the centers of the Earth and moon.)

December 5 is also the farthest quarter moon

Although the 3rd quarter moon on December 5 won’t look different from any other quarter moon, it will also be the farthest quarter moon from Earth in 2023. This is not a complete coincidence: as the Earth-moon distance gets larger, the percentage of the moon’s face that is lit up increases.

Similarly, it is no coincidence that December 5 falls near perihelion (early January), when Earth is closest to the sun. A smaller Earth-sun distance also leads to a greater percentage of the moon’s face being lit up.

Lesser-known moon dates for 2024

The moon’s orbit around Earth is never the same from one lunar month to the next, leading to events such as supermoons and micromoons.

So, again, in 2023, the most-illuminated quarter moon will be the 3rd quarter moon of December 5. And, in 2024, the most-illuminated quarter moon will be the 3rd quarter moon of December 22.

Here are seven lesser-known lunar events for 2024.

January 25: Longest moon phase of 2024. There will be 8.225 days between full moon on January 25 and 3rd quarter moon on February 2.

March 10: Closest moon of 2024. The most extreme Earth-moon distances occur at new moon or full moon. At new moon on March 10, the moon will be 221,764 miles (356,895 km) away.

May 30: Shortest lunar month of 2024. The moon will cycle through all its phases – from 3rd quarter moon on May 30 to 3rd quarter moon on June 28 – in 29.195 days.

August 19: Shortest moon phase of 2024. The moon will take 6.625 days to wane from full moon on August 19 to 3rd quarter moon on August 26.

October 2: Farthest moon of 2024. At new moon on October 2, the distance to the moon will be 252,597 miles (406,516 km).

November 23: Longest lunar month of 2024. It will take the moon 29.868 days to go from 3rd quarter on November 23 to 3rd quarter on December 22.

December 22: Most-illuminated quarter moon of 2024. And so it comes around again!

Bottom line: Some quarter moons are fuller than others! The most-illuminated quarter moon of 2023 is on December 5. This happens when the moon is in a slightly different position in its orbit … a little bit after 3rd quarter, or a little bit before 1st quarter. Learn more unique moon dates for 2024.

The post 2023’s most-illuminated quarter moon is tonight first appeared on EarthSky.

Written by Graham Jones and reprinted with permission from timeanddate.com. Additional edits by EarthSky.

Solar and lunar eclipses can occur only during a short period of time known as an eclipse season. No two eclipse seasons are the same, and some are particularly noteworthy. The upcoming eclipse season – May-June 2021 – will produce a pair of full eclipses: a total lunar eclipse on May 26, 2021, and an annular solar eclipse on June 10, 2021. This kind of pairing isn’t rare. It happens, on average, once every eight years or so. Still, this upcoming pair of eclipses is unusual in that we’ll have an especially short lunar eclipse and an especially long solar eclipse. You can watch both these eclipses live on timeanddate.com.

When two full eclipses are squeezed into a single fortnight, the alignment of the Earth, moon, and sun for each event is only just good enough to produce a totality or an annularity.

A short lunar eclipse … In the total lunar eclipse on May 26, 2021, the totality, when the moon is fully submerged in Earth’s shadow, will last a little over 14 minutes. That duration will make it the 10th-shortest totality for any lunar eclipse for the approximately 1,000-year span between the years 1600 and 2599. In terms of the total worldwide duration of the eclipse, which includes partial and penumbral phases, the May 26 event is even more exceptional: it is the second-shortest of all 693 total lunar eclipses in the same 1,000-year span.

… and a long solar eclipse. Within the same period, the June 10 annular solar eclipse is also notable for its length. Although it is not particularly long when compared to solar eclipses in general, it stands out as having the fifth-longest worldwide duration (including partial phases) of any total or annular solar eclipse that is paired with a total lunar eclipse in the same eclipse season.

Between the years 1600 and 2599, there are 2,108 eclipse seasons. Of these, only 126 seasons contain a pair of full eclipses: one total or annular solar eclipse, plus one total lunar eclipse.

At timeanddate.com, we looked at the worldwide duration of each eclipse in these pairs. This is the length of time between the first and last moments the eclipse is visible from somewhere in the world, including partial and penumbral phases.

Generally speaking, the better the alignment of the Earth, moon, and sun, the longer the worldwide duration of the eclipse. (There are several ways to measure how closely the three bodies are aligned, such as the magnitude of the eclipse, or a more technical number referred to as gamma. However, for fun, we looked at the total length of the eclipse in seconds.)

How the May-June 2021 eclipses compare to others. The worldwide duration of the annular solar eclipse on June 10, 2021, is 17,939 seconds, or just under five hours. For a full solar eclipse that occurs in the same season as a total lunar eclipse, this turns out to be unusually long: it is the fifth-longest solar eclipse in our 1,000-year sample of 126 pairs of full eclipses.

This means that the worldwide duration of the total lunar eclipse on May 26, 2021 is likely to be short … and indeed it is. Its total length of 18,127 seconds, or just over five hours, might not seem that quick. But for a lunar eclipse that includes penumbral, partial, and total phases, it is exceptionally fast.

Across all 2,108 eclipse seasons in the period 1600 to 2599, there are 695 total lunar eclipses. Only one of these has a shorter worldwide duration than the May 2021 eclipse. It is literally a few seconds shorter – four seconds, to be precise – and it will occur 345 years from now (on May 25, 2366).

If we consider only totality – in other words, if we ignore the partial and the penumbral phases – the May 2021 eclipse has a duration of 858 seconds (about 14 minutes). By this criteria, it is the 10th-shortest of all 695 total lunar eclipses in our sample period of one millennium.

Eclipses need a new moon or a full moon. The basic requirement for a solar eclipse is a new moon, which occurs when the moon passes between the Earth and the sun. A lunar eclipse requires a full moon, when the moon is on the opposite side of Earth from the sun.

The moon takes around 29.5 days to go through all its phases, and new moons and full moons are separated by about two weeks.

Eclipses don’t happen every month. The moon’s orbit around Earth is tilted by about 5.1 degrees to Earth’s orbit around the sun. This is why eclipses don’t happen every month: at new moon and at full moon, more often than not, the moon is too high or too low to align precisely with the Earth and the sun.

Eclipses come in seasons. About every six months, Earth comes to a sweet spot in its orbit where a perfect – or almost perfect – three-way alignment of the Earth, moon, and sun can occur. Each sweet spot lasts for about 34.5 days: an eclipse season.

If there is a new moon near the middle of an eclipse season, it will form a straight line with the Earth and the sun. The result will be a total solar eclipse, or an annular solar eclipse, if the moon is too far from Earth to cover the sun completely. In a similar way, a full moon near the middle of an eclipse season will produce a total lunar eclipse.

Read more: What is a hybrid solar eclipse?

Read more: What is an eclipse season?

On the other hand, if a new moon or a full moon comes near the beginning or end of an eclipse season, the three-way alignment will be not quite perfect. In this case, the result will be either a partial solar eclipse, a partial lunar eclipse, or, if the moon passes through only the faint outer part of Earth’s shadow, a penumbral lunar eclipse.

Eclipses guaranteed. Since a lunar month (the time taken for the moon to go from new to full to new again) is only 29.5 days, each eclipse season is guaranteed to produce – somewhere in the world – one solar eclipse and one lunar eclipse. There can also be a second solar or lunar eclipse, if the first one occurs in the first few days of the season.

Eclipses in balance. In most cases, the solar and lunar eclipses within each season balance each other: if one is a full eclipse, the other tends to be partial. To put it another way, if the alignment of the Earth, moon, and sun is perfect for one eclipse, the other eclipse will likely be near the beginning or end of the season, when the alignment is less perfect.

For example, the “Great American” total solar eclipse of August 21, 2017, was preceded by a small partial lunar eclipse 14 days earlier. And the total lunar eclipse of July 27, 2018 – the longest of the 21st century – was sandwiched between two small partial solar eclipses (on July 13 and August 11).

Two full eclipses in one season. Occasionally, however, both the new moon and the full moon fall close enough to the midway point of a season to produce a pair of full eclipses. It is possible to fit in two full eclipses like this, but it’s a squeeze: in each case, the alignment of the Earth, moon, and sun is only just good enough to produce a full eclipse.

Again, there is a balance between the two eclipses. The better the alignment is for one, the worse it will be for the other. This is what makes the forthcoming eclipse season especially interesting.

Note on the accuracy of eclipse predictions. All eclipse predictions contain a small margin of error. One of the uncertainties in lunar eclipse calculations, for example, is that the atmosphere gives Earth’s shadow a fuzzy edge.

This can lead to borderline cases such as October 17, 2024. We at timeanddate.com classify this as an “almost” lunar eclipse, while some sources list it as a penumbral eclipse.

Bottom line: Solar and lunar eclipses can only occur during a short period of time known as an eclipse season. The upcoming May-June 2021 eclipse season is an unusual one. Here’s how to understand it in the context of 1,000 years of eclipses.

Read more: Total eclipse of year’s closest supermoon on May 26, 2021

Read more: Annular solar eclipse on June 10, 2021

Read more: When is the next total solar eclipse in North America?

The post May-June 2021: A special pair of eclipses first appeared on EarthSky.

This past summer, solar physicist Kanya Kusano of Japan, and his colleagues, published a new paper in the prestigious journal Science, outlining a new method for predicting potentially dangerous solar flares. The method isn’t perfect; tests using solar observations acquired in 2008 to 2019 resulted in some false negatives and false positives. Yet, impressively, the method successfully predicted seven out of nine of the biggest X-class flares – the most powerful kind of solar flares – from the last solar cycle. The method also provided the exact location where each flare would begin and set limits on how powerful it would be. Graham Jones – who is based in Japan – had an opportunity to interview Kanya Kusano about this work. His interview is below.

About solar flares. They are brief eruptions of intense high-energy radiation from the sun’s surface. They’re associated with sunspots, coronal mass ejections and other signs of high activity on the sun during its 11-year cycle. The current cycle – Cycle 25 – has now begun, scientists say. Activity on the sun creates what’s known as space weather. Accurate forecasts of space weather are important, because a big solar flare hurtle charged particles toward Earth and cause outages in our electrical power grids and disturbances of satellites in orbit.

Understanding when and why these powerful solar flares happen has been a difficult challenge in astrophysics. Much of the work has been on theoretical mathematical models, as scientists have tried to understand the exact physics behind solar flares and their resulting coronal mass ejections. All this work has the ultimate goal of predicting storms on the sun.

What sets Kusano’s team’s method apart is that it’s physical, rather than being based on models. In other words, these scientists used NASA’s Solar Dynamics Observatory (SDO) data to make a 3-D picture – a magnetic map – of the sun.

Their approach opens a new direction for solar flare prediction research. Kusano spoke about about their work below.

Jones: What is the Institute for Space-Earth Environmental Research, and what’s your role?

Kusano: The human environment is so extended, it even spreads into space. Our institute was established in 2015 to combine space science and Earth science. My background is in astrophysics, but I used to work for the Japan Agency for Marine-Earth Science and Technology, where I developed simulations of clouds and rainfall. I’m a theoretician, but I always try to apply theory to some kind of practical benefit. Space weather forecasting is a field where basic science and practical application should be combined.

Jones: What is a solar flare, and why do scientists study them?

Kusano: A solar flare a kind of explosion on the sun. The driving force is the energy stored in the sun’s magnetic field. This magnetic energy builds up slowly over a very long time, which then is suddenly released as radiation and high-energy particles.

It’s just like an avalanche on a mountain: the snow accumulates over many days until the gravitational energy is released in an avalanche.

The first reason we want to study these flares on the sun is that phenomena that occur suddenly are very interesting science subjects. What determines the onset of an explosion? A typhoon, which grows quickly from a low pressure system, is another example of an explosion in an atmospheric system.

The second reason is to protect our society. The distribution of solar flares is similar to earthquakes: we have many small solar flares, and a big one is very rare. However, when a big flare occurs, the impact on our economy and society may be enormous. Satellites may be damaged, and the electrical power grid may be damaged over a very wide area.

The only way to mitigate such kind of impact is with prediction.

Jones: Why has it taken so long to come up with a way to predict solar flares?

Kusano: Solar flares were discovered in 1859 by Richard Carrington, a British astronomer. People studied them for more than 100 years.

But in the last two or three decades, our knowledge has improved enormously because of very high resolution observations by satellite. We now understand that a solar flare is an explosion of magnetic energy.

However, what determines when the solar flare occurs? That is still a mysterious problem.

Jones: How are you solving this problem?

Kusano: NASA’s Solar Dynamics Observatory (SDO) satellite provides magnetic data on the solar surface. It is impossible to directly observe the magnetic field in three dimensions, so we have developed software which can calculate the three-dimensional field from the surface data. Then we combine this with theory. Instability of the magnetic field is triggered by magnetic reconnection, where the field lines swap around. If we can find some position where a small amount of magnetic reconnection could trigger instability, then we can predict that a big flare should start from there. It is similar to that avalanche. If you have thick snow on a mountain, theory can tell us how small a crack could trigger an avalanche at any position.

View the sun now, via SDO

Jones: Your latest paper is a proof of concept. How long will it be before you can start making forecasts of solar flares on a regular basis?

Kusano: Currently our scheme requires a big, heavy calculation. We use a supercomputer here in Japan. However, in order to produce one prediction, more than three hours of computation is required. It also takes more than several hours to get the SDO satellite data. In order to make our method work for creating practical, operational forecasts of solar flares we have to accelerate the data acquisition and computation.

I believe that within a couple of years we can make some kind of operational forecast using our scheme.

Jones: Many people worry about another large solar flare happening in a way that would affect our technologies on Earth – another event like the Carrington Event, the largest space super-storm in recorded history – which took place in 1859 before the advent of the electrical grids and Earth-orbiting satellites that are so susceptible to these events. Do you worry about a big solar flare happening?

Kusano: I do. I worry about an extreme event. We want to protect our society from a space-weather disaster. Our scheme can predict a solar flare several hours before the onset of the flare, but we cannot predict a solar flare in the next week.

There are many such kinds of risks we should be concerned about in our society. And maybe science is the only way to think about them.

Jones: Thank you, Dr. Kusano.

Bottom line: A team of researchers in Japan has developed a physics-based method for predicting large solar flares, including powerful and potentially dangerous X-flares. These flares on the sun – and their resulting coronal mass ejections – pose risks for earthly technologies. Accurate prediction of the flares has been a challenge, but this new method seems to offer a leap forward in creating more accurate forecasts of space weather.

Source: A physics-based method that can predict imminent large solar flares

Read more: NASA sun data helps new model predict big solar flares

Read more: We can now predict dangerous solar flares a day before they happen

Read more: How likely is another Carrington Event?

The post A new method for predicting large solar flares first appeared on EarthSky.

By Graham Jones

If the earth is a spaceship, we all have a window seat.

The sky is there for everyone, and the fundamentals of skywatching — from the rhythm of the moon, to the pattern of the stars — have remained unchanged throughout human history.

Yet inequalities exist. Both within the astronomy community and beyond, in the area of education and public outreach, people face barriers because of their age, ethnicity, gender, culture, ability or disability, religion, race, sexuality or a combination of these factors.

Last month (November 2019), more than 100 members of the International Astronomical Union (IAU) gathered in Tokyo to discuss a roadmap to action. Astronomy for Equity, Diversity and Inclusion was a four-day symposium hosted by the National Astronomical Observatory of Japan; its aims were to show how diversity and inclusion produce better science and innovation, and to focus on the steps needed to achieve change.

When it comes to the challenge of communicating astronomy to communities around the world, some of the proposed solutions were to be found surprisingly close to people’s homes.

Ikechukwu Anthony Obi works for the Center for Basic Space Science at Nigeria’s National Space Research and Development Agency. He is clear about the difficulties of bringing astronomy to the poorest communities of Africa’s most populous country: problems with the supply of electricity, little or no funding, and misinformation.

At the same time, Obi is equally clear about the opportunities. He said:

Rural settings have the clearest and darkest sky. There are also no city-life distractions, and people have a sound knowledge of cultural astronomy.

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Obi’s vision for community astronomy in Nigeria is based around low-cost battery-powered equipment, and virtual observatory tools. He explained:

Credit-card-sized Raspberry Pi computers can be set up in schools and used for giving hands-on experience of astronomical data analysis. We can also do astrophotography with locally made telescopes.

One particularly ingenious idea involves a piece of technology that can be seen on the roofs of dwellings across Nigeria. Obi said:

Satellite TV dishes are everywhere. Nigerians are heavy internet users and telecom consumers, and there is a booming entertainment industry. With a Raspberry Pi and a satellite finder, we can adapt these locally available satellite dishes to provide early exposure to radio astronomy.

Students and teachers alike are thrilled by the science that can be done with these set-ups. It enables them to appreciate the scientific principles underlying the already known and well-practiced cultural astronomy.

The importance of working in harmony with indigenous cultural knowledge was also the message of Nurul Fatini Jaafar, an ethno-astronomy researcher at the University of Malaya in Kuala Lumpur. She works with the Semelai people of Lake Bera, in the center of the Malaysian peninsula.

Nurul’s research involves participant observation and in-depth interviews. She said:

In a typical setting where both men and women are present, the men will always respond to my questions. The women will keep silent.

However, when only women are present, things change. Nurul, who holds a degree in physics and astronomy, said:

I was taken by surprise to learn that the women actually understand a lot about astronomy. They possess knowledge about stellar positioning, celestial forecasts and moon phases. Their comprehension of the sky is one step ahead of the typical male.

Sadly, this knowledge is not always valued. Nurul said:

Indigenous children who are enrolled in national schools — which instill the western science perspective — are unaware of the reliability of their traditional science. Their knowledge system is seen as anecdotal and unscientific, and there is a presumption that their parents have no authority towards scientific knowledge. As a result, their parents cannot guide them with science subjects at home.

Nurul is part of a pilot project to involve women in science. She said:

We have started to explore astronomical topics from a cultural perspective. We are acquainting them with smartphones that are equipped with astronomical software, and are showing them the projection of the sky. We hope that the women will help us to integrate the two paradigms of western science and indigenous knowledge.

These women have always wanted a bigger role in educating their children in science. Now they are looking forward to the moment when their dreams finally materialize.

Bottom line: The IAU is working on a roadmap to better science and innovation through equity, diversity and inclusion.

The post Bringing community astronomy to rural Africa first appeared on EarthSky.

By Graham Jones of Ten Sentences and Richard Gelderman, an astronomy professor and director of the Hardin Planetarium at Western Kentucky University. Interview by Richard Gelderman.

After losing her sight in her 20s, Wanda Díaz Merced became a pioneer of sonification, a technique for turning data into sounds. Her TED talk on How a blind astronomer found a way to hear the stars is one of TED’s most-watched astronomy videos. We caught up with Wanda at the General Assembly of the International Astronomical Union (IAU) in Vienna earlier this year.

Scientists used data sonification to transform a photo of sunrise on Mars into a piece of music.

Wanda Díaz Merced was deep in a conversation about her effort to draw more information out of an important data set. I was waiting to break into this discussion, introduce myself, and ask a question of this respected astronomer. To any onlooker, the energy and brightness shared as she expounded on the details of her research were no different from what we experience in encounter after encounter, all through each day, at the IAU General Assembly.

When I got the chance to introduce myself, Wanda’s hand was so confidently extended toward mine that I momentarily wondered if Wanda had at least partial use of her sight. This caught my attention, because I was there to ask a question about how she, as a person with complete loss of her eyesight, uses sound to experience multi-dimensional data sets and images.

Wanda was 19 years old and in the U.S. studying mathematics and physics at university when her first symptoms of blind spots occurred. Wanda was born with diabetic retinopathy, and it slowly destroyed her eyesight until she was completely blind at age 29.

During these difficult young adult years, Wanda resolved to find a way to continue her study of astronomy. At NASA Goddard Space Flight Center during a summer 2005 ACCESS internship, heliophysicist Robert Candey agreed that Wanda should be able to get as deeply involved with the data as any sighted astronomer. She used that encouragement to develop methods to turn plots into dimensions of time and pitch, loudness, or duration. As her efforts increased, they became the foundation of her groundbreaking Ph.D. thesis from the University of Glasgow.

Wanda announced to the audience of her 2016 TED talk:

Information access empowers us to flourish.

However, creating a scientific playing field that is not dependent upon access to all five senses is only one aspect of Wanda’s research.

During our conversation at the IAU’s Inspiring Stars booth, I noted with some surprise as Wanda seamlessly transitioned from facing me, to pointing out a nearby demo, to turning to type on her laptop. She explained:

Without sight, I require a sequence to orient me.

Her work with sonification of digital data is an example of a similar organizational framework.

Astronomical research frequently involves the scrutiny of representations of digital data. Visual interpretation of plots is one way to pursue this goal, but the results of Wanda’s research show that combining sensory modalities makes anyone better at such interpretation.

The computer application interprets brightness, wavelength, position, or temporal information into pitch, loudness or rhythm changing over time. It is these changes that Wanda listens for. She said:

I keep vigilant for the unexpected. Sensitivity to events increases when you use sound. In noisy data, those in our studies identify more peaks, dips, and pulses than just with sight.

Bottom line: Astronomer Wanda Díaz Merced explains how turning digital data into sound can help us find the patterns hidden in the information we receive from telescopes.

Read about how tactile models of the constellations, moon and planets can give people – blind or sighted – a better appreciation of the universe

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The post Listening to the patterns of the universe first appeared on EarthSky.

By Graham Jones of Ten Sentences and Richard Gelderman, an astronomy professor and director of the Hardin Planetarium at Western Kentucky University.

That which distinguishes astronomy from all the other sciences is this: it deals with objects we cannot touch.

So wrote the great astronomer Edward Walter Maunder in 1912. Yet tactile astronomy, originally developed for blind and partially sighted people, can help everyone improve their understanding of the universe – even people with perfect eyesight. Amelia Ortiz Gil, from the Astronomical Observatory of the University of Valencia in Spain, tells her story.

Amelia Ortiz Gil: It all started when a school for children with disabilities asked if they could visit our observatory. We started to work with their teachers, saying “OK, these are the things that we do with other schools. How can we adapt these to the needs of your children?” From here, we were asked if we could organize some special activities for the International Year of Astronomy in 2009. We were lucky because we found a science communicator in Argentina, Sebastián Musso, who had organized a planetarium show for the blind, and he shared his ideas with us.

We made tactile domes with some of the northern hemisphere constellations engraved on them, and wrote a script and a soundtrack for a planetarium show: The Sky In Your Hands. Our premiere was at L’Hemisfèric, a planetarium and IMAX Cinema here in Valencia.

The planetarium has speakers distributed across the dome. In the soundtrack, each constellation was associated with a sound, which came from the speaker that was closest in the ceiling to that star. So this, together with the tactile domes, gave people the distribution of the stars through the use of touch and sound.

This was important because my colleagues had found that some blind people thought that all the stars were packed together in one single spot in the sky. When you work in this area you sometimes have to find misconceptions that you would never think of beforehand; this was one of them.

The show was a moving experience. Some people, who had lost their vision later in life, were crying because they said they had remembered what they used to see when they were kids. Others were telling us that they had finally grasped concepts they had read about but not really understood: the distribution of stars, the shape of the constellations, and things like that.

It was a mixed audience, and people who were not blind also enjoyed the show. They enjoyed touching the models and realizing that the thicker stars are the brightest ones, and the smaller ones shine a bit less. You cannot always grasp that when you are just looking at a lot of stars in the dome.

Kids also enjoyed the program. It’s nice to touch! We have a natural inclination to touch everything. And there was an exchange of information between blind and non-blind people. Because they are using different sensory channels they perceive differences that the other one might not perceive. So it helped everybody.

A touch of the universe

After the tactile sky, our next challenge was the tactile moon. We thought about doing a topographical representation of the moon. But would that really be useful? We felt, no, it would be nicer to have a tactile representation of our visual impression of the moon. For example, we are used to seeing the rays around craters, and you miss that when you use a topographical representation because the rays have no height.

We took visual data from Clementine’s map of the moon (the NASA probe that mapped the whole surface of the moon) and translated it into height on a globe. The brighter features have a greater height than the darker features; the maria – the dark seas on the map – are smooth on our globe.

We have a meridian that is the border between the near side and the far side. An engraved T marks the north pole, with the vertical line pointing to the near side. We also put some braille letters close to some of the features, and created a braille key. We like to give people this autonomy – this freedom – to explore the moon for themselves.

Blind people conceive the world in a different way; they have different misconceptions to the rest of us. For example, one blind person said – this is recorded in a video, it’s amazing – “Hey, so the moon is a globe?!” Until then her tactile experience of the moon had been in books with just a flat map, so she thought the moon was a flat disk. So that was another misconception that I didn’t expect to find, but is there.

After that we thought, why stop at the moon? So now we have topological models of Mars, Venus, Mercury and the Earth. And one of our team, Jordi Burguet, has produced some wonderful software called Mapelia – you can take any map you can think of and convert it into a tactile sphere that can be printed on a 3-D printer.

Making the models helped me to better understand the surface of these planets. With Mars, you really see how flat and smooth the northern hemisphere is compared to the south. And Venus has many complicated features.

And so we are giving people tactile models of things that nobody can see, neither blind nor sighted people. OK, you can see a bit of Mars through a telescope, but you cannot see anything of Venus. No human being has a direct visual experience of the surface of Venus.

Note: All of the resources Amelia mentioned in this article — tactile domes and planets, software, soundtracks and guides — are available under a Creative Commons license at A Touch of the Universe. “We want to share this with everyone in the world,” she said.

Bottom line: Astronomer Amelia Ortiz Gil explains how tactile models of the constellations, moon and planets can give people – blind or sighted – a better appreciation of the universe.

Read about sonification – how a blind astronomer found a way to hear the stars

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The post Astronomy beyond sight first appeared on EarthSky.

By Graham Jones of tensentences.com

The coming total solar eclipse of August 21, 2017 – seems certain to inspire a new generation of eclipse chasers. After that eclipse, when is the next one? Rather a long time, it turns out. Apart from four partial eclipses, mostly taking place at extreme southerly or northerly latitudes, we have to wait until July 2, 2019 for the next total solar eclipse, which cuts across Chile and Argentina and ends at sunset to the south of Buenos Aires.

This raises a question: why? Since the moon orbits Earth once a month (to be precise, it passes between the Earth and sun every 29.53 days), why don’t we have 12 or 13 eclipses every year? I organize solar eclipse workshops for students, and this question has proven thought-provoking. The easy answer is that the moon’s orbit around Earth is tilted, by five degrees, to the plane of Earth’s orbit around the sun. As a result, from our viewpoint on Earth, the moon normally passes either above or below the sun each month at new moon.

But there’s a deeper question: why is the moon’s orbit tilted? Students are often surprised to learn that we don’t have a definite answer to this question. In fact, it’s a puzzle known as the lunar inclination problem.

In late 2015, two planetary scientists – Kaveh Pahlevan and Alessandro Morbidelli – published an elegant solution. They had run computer simulations to look at the effect of collisionless encounters (near-misses) between the Earth-moon system and large objects, similar to what we today call asteroids, leftover from the formation of the inner planets. Their results – published in the peer-reviewed journal Nature – showed that these objects could have gravitationally jostled the moon into a tilted orbit.

Some of these large objects would have eventually collided with Earth – and this provides an answer to another puzzle. When Earth formed, precious metals such as platinum and gold would have been carried down to our planet’s iron core. (Precious metals are siderophile, which means iron-loving.) Yet platinum and gold can be found at Earth’s surface in relatively high amounts, which suggests they were delivered to Earth later on.

And so Pahlevan and Morbidelli’s large objects become multi-taskers. First, through collisionless encounters, they jostle the moon into a tilted orbit. Next, by crashing into the earth, they deliver precious metals. Robin Canup, another planetary scientist, highlighted the significance of this dual role in another Nature article, when she wrote:

Had such a population of objects not existed, the moon might be orbiting in Earth’s orbital plane, with total solar eclipses occurring as a spectacular monthly event. But our jewellery would be much less impressive – made from tin and copper, rather than from platinum and gold.

Kaveh Pahlevan is currently based at the School of Earth and Space Exploration at Arizona State University. I asked him about his work – beginning with two questions from students at my eclipse workshops. That is, people are often surprised to learn that there’s much about the moon we don’t fully understand, including the question of how it formed. As one student asked:

We’ve done a flyby of Pluto; we’ve discovered exoplanets; we study distant galaxies, quasars and black holes. So how is it possible that we still don’t know for certain about the moon?

Pahlevan answered:

If you had lived in the 17th or 18th century, you would have made the same observation about the origin of living things: we had circumnavigated the globe; we had discovered distant lands and seas, with flora and fauna we had never imagined; yet we still didn’t understand the origin of species. It is easier to take an inventory of what is observable today than to try to infer origin events which happened long ago and which are not observable.

When a crime happens, investigative police quickly arrive on the scene and try to preserve the evidence. In the case of the moon’s origin, there was a violent event, but there were no witnesses, and we are arriving on the scene five billion years late! Most of the evidence of this event has been obliterated over the ensuing aeons. We have to look at the few remaining pieces of evidence to try to put together a story. It’s a challenge. But it’s a part of our own origin story, and that’s what’s captivating.

When (if ever) will we be able to point to a definitive answer about how the Earth-moon system formed? Pahlevan said:

Developments are seldom definitive. In order to make progress, we have to acknowledge our ignorance. Even when we have ideas that seem to have some explanatory power, we maintain them alongside some doubt, and acknowledge that they might be wrong. It is human to want to have stories with explanatory power: this is the source of origin myths the world over. But with our scientific origin theories, we have learned that they are always tentative. We have to be aware of the limitations of our knowledge if we are to make progress.

One area that is promising for progress involves sample data. The Apollo astronauts brought back nearly 400 kilograms [nearly 900 pounds] of lunar rocks during their brief lunar sojourns in the 1960s and ’70s. The technology to analyze the composition of these rocks has improved enormously in the intervening half-century. So we are now able to tease out some signals from the lunar rocks that we couldn’t before.

This is exciting because the atoms in the lunar rocks – the atoms in the moon – were there during the lunar origin event and, in some sense, they are witnesses to what happened. Using the newly available signatures that are recorded in these samples to test and develop our ideas is an area that’s ripe for progress.

Pahlevan’s 2015 paper with Alessandro Morbidelli looks at the effect of the collisionless encounters that preceded collisions between the Earth and other bodies in the inner solar system. I asked Pahlevan how he and Morbidelli originally thought of this idea, and later developed it. He said:

Several years ago, I attended a conference in Ascona, Switzerland, in which Dr. Morbidelli gave a talk about the formation of the terrestrial planets. He mentioned that the moon-forming impact may have been the last giant impact in the formation history of the Earth, perhaps because earlier-generated satellites would have been gravitationally lost via encounters with other massive bodies in the inner solar system, which was a very crowded place at the time. I knew that the lunar inclination was an open scientific problem, and it was there that the seeds for this project were planted. I went home and did some calculations.

I later approached Dr. Morbidelli at another conference about applying collisionless encounters to the lunar inclination problem, and he expressed interest in the idea and invited me to Nice, France, in 2012 to work on this project. Dr Morbidelli has a fluency with numerical integrations that is very rare, so once the idea was in place, things progressed quickly and it became immediately clear that there was potential there.

Some professional astronomers spend all their time in front of a computer and never actually look up at the sky. You are a planetary scientist, not an astronomer, but do you ever spend time gazing up at the objects of your study?

I’m a theorist so I don’t spend much time at telescopes or in places where the sky is dark. Sometimes, when we’re outside, my non-scientist friends ask me ‘Where is the moon?’ I have no idea where it is. But sometimes, when I’m going about my day, I do notice it in the sky. It’s a reminder to get back to work.

Bottom line: The five-degree tilt of the moon’s orbit – which is the reason solar eclipses are rare events – has recently been explained by collisionless encounters (near-misses) between the Earth-moon system and large objects leftover from the formation of the inner solar system.

The post Mystery of the moon’s tilted orbit first appeared on EarthSky.

By Graham Jones of www.tensentences.com

“So where exactly is the moon right now?”

We were outside a cafe in Palu, on the Indonesian island of Sulawesi, two days before the total solar eclipse of March 9, 2016. I was sitting with my new friends, a group of friendly and inquisitive locals that had formed the moment I sat down – and had been growing ever since.

It was the middle of the afternoon, so I waved my hand in the direction of the sun and said:

Well, the moon is over there, getting closer and closer to the sun.

My new friend patiently persisted:

Yes, but where EXACTLY is the moon right now?

Wow, I thought, that’s a good question, and promptly began to have a minor panic about how difficult this cross-examination might become. I was already feeling a bit discombobulated after picking up a leaflet about the eclipse at the airport in Jakarta on my way to Palu. It was an excellent publication from the Ministry of Tourism, and included a list of timings for the eclipse at various locations across the Indonesian archipelago. At the bottom, however, was an ominous note: “This schedule is subject to change without prior notice.”

Hmm, that didn’t sound good. I was due to take part in an international seminar about eclipses at Tadulako University (Untad) on March 8. Other speakers included Thomas Djamaluddin, the chairman of Indonesia’s national space agency, and Miquel Serra-Ricart, from the Instituto de Astrofísica de Canarias in Spain. It would be embarrassing if we were standing there talking about the elegant certainty of Newtonian physics when everything suddenly went dark outside the window.

Back at the cafe, after much drawing of shapes in the air, we agreed that we were dealing with a waning crescent moon, which travels across the sky from east to west ahead of the sun. Eventually, we worked out that the moon would be somewhere between the sun and the western horizon, where it would soon be setting, lost in the bright glare of the sun.

For me, this conversation underlined three things. One, eclipses are social events – they have a unique power for bringing people together around a shared experience. Two, eclipses can provide us with all kinds of teachable moments – they are a tremendous opportunity to think more about science and nature. Three, eclipses truly are global phenomena that add a wonderful dose of serendipity to life – were it not for the quirk of fate that sent the moon’s shadow this way, I would never have discovered that Palu is home to the warmest and most welcoming people you could ever hope to meet.

Nor would I have had the opportunity to find out about some of the extraordinary work that is going at Untad, whose beautiful campus offers stunning views across Palu Bay. Darmawati Darwis runs the university’s Centre for Organic Electronics (COE), a sister organization of the pioneering COE founded by Paul Dastoor at Newcastle University in Australia. Dr Darwis’s interdisciplinary team is helping to develop a new range of organic solar cells; in a rapidly developing country of 260 million people that is blessed by year-round sunshine but plagued by power cuts, this is some of the most exciting and important research going on in Indonesia today.

On the subject of serendipity (although this is, in fact, more an example of sagacity!) enormous thanks must go to EarthSky for helping to bring about a fantastic collaboration between Tadulako University and Western Kentucky University (WKU) in the USA. Last November, EarthSky published an article about a series of workshops I was organizing with Untad. These workshops were a part of a project I run called Global Communication and Science, which aims to help students improve their English-language skills, gain a deeper appreciation of the wonders of science, and connect with students in other countries. (This project has been generously supported by the airline Garuda Indonesia as part of its community development program.)

The article was seen by Richard Gelderman, a professor of physics and astronomy at WKU, who contacted me to say he would be taking a team to Palu as part of CATE, a citizen-science project that is aiming to collect 90 minutes’ worth of data on the solar corona during next year’s coast-to-coast eclipse across the continental USA. Within a few weeks, a cross-border team of students from Untad and WKU were working together online to select a site in Palu for the CATE telescope. Shortly after that, our team was approached by NASA’s Earth Science Division to ask if we could test some experiments during the eclipse for its GLOBE environmental program.

Overall this became a story of science, teamwork, friendship and – of course – the drama of totality itself. In an interview with sky-live.tv shortly before the eclipse, Dr. Gelderman said:

I’m hoping that the moment the sun disappears in the middle of the morning, my body will react in a very primal, caveman way. Not the type of logical thinking that I’m used to as a scientist, but a purely artistic, emotional feeling of, holy cow, the sun just disappeared.

For anyone looking for an excuse to visit Palu – which has rightly been described as “a piece of paradise on the equator”, and is home to the most delicious fried banana known to mankind – please note that there are only 15 years to go until the city’s next big astronomical extravaganza. Palu will be right on the center line for the annular eclipse of May 21, 2031…

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Bottom line: The solar eclipse of March 9, 2016 brought students from around the world to Palu, Indonsia.

The post Eclipse stories from Indonesia first appeared on EarthSky.

By Graham Jones of www.tensentences.com

Science is one of the few things in the world that truly transcends national borders. November, 2015, for example, marked 15 years of continuous human habitation aboard the International Space Station (ISS), the orbiting laboratory operated by five space agencies. Yet cross-border communication is never without its difficulties. Julie Robinson, NASA’s chief scientist for the ISS, tells the story about the time JAXA, the Japanese space agency, asked NASA to collaborate on a piece of equipment. The Americans thought that the Japanese wanted to collaborate on building the equipment; they went back with some questions. At one point in the discussion, NASA suddenly realized that JAXA didn’t want help building it. It was already built. JAXA had actually been asking if NASA wanted to collaborate on using the equipment. Dr Robinson commented:

The thing is, the discussion had been going on for two years before anyone realized.

The global nature of science, plus the challenge of global communication, are two central ideas behind a project organized by tensentences.com that will bring together university students in Indonesia and Japan – and elsewhere in the world – in 2016. A series of Global Communication and Science workshops will help students of all subjects improve their English-language skills, and gain a deeper appreciation of the wonders of science. The project will also connect Indonesian and Japanese students online for a series of cross-border team-working activities.

The theme of the workshops is the forthcoming solar eclipse of March 8-9 2016, which will be a partial eclipse in large areas of East Asia, South-East Asia, Australia and Hawaii, and a total eclipse along a narrow path of totality running across the Indonesian islands of Sumatra, Kalimantan, Sulawesi and North Maluku. (Note: in Hawaii, the partial eclipse will take place during the two hours before sunset on March 8, while in Asia it’ll be March 9)

A solar eclipse – which, generally speaking, happens somewhere in the world two or three times a year – is one of the most spectacular things in science. It is a unique and powerful teachable moment; it is, literally, a stellar opportunity to educate and inspire.

The host university in Indonesia is Tadulako University in Palu, Central Sulawesi, which will experience two minutes of totality. Marsetyo Marsetyo, the head of the university’s international office, said:

More than 3,000 scientists from around the world will be coming to Palu to observe the eclipse.

For two minutes on the morning of March 9, 2016, Palu will be the center of the scientific world. So this really is a golden opportunity for our students to think about global communication and science.

Garuda Indonesia, the national airline of Indonesia, is sponsoring the workshops as part of its community development program. Fikdanel Thaufik, the airline’s vice-president for Japan, Korea and the U.S. said:

Education is a key part of our commitment to corporate social responsibility.

We are delighted to be supporting this project, which will build bridges between students in Indonesia and Japan, and help students to become more effective global citizens.

The workshops will be a mixture of science, astronomy and language activities, including script read-throughs of science-fiction movies.

An online part of the program, which will give students the opportunity to collaborate in cross-border groups, will also involve universities that are preparing for eclipses beyond March 9, 2015. These include the University of Mahajanga in Madagascar – an island off the southeast coast of Africa – where students will witness two-and-a-half minutes of annularity during an annular eclipse on September 1, 2016.

Looking even further ahead, 2017 will bring two solar eclipses. One is the annular eclipse of February 26, 2017, across parts of Chile, Argentina, Angola, Zambia and the Congo. Then there is what some are calling the Great American Eclipse of August 21, 2017, where the path of totality will run coast to coast from Oregon to South Carolina.

If your school, college or university is interested in joining the Global Communication and Science project, please contact us at www.tensentences.com.

Supermoon total eclipse March 8-9

Bottom line: Tadulako University and Garuda Indonesia are helping to support a series of English-language workshops in Indonesia and Japan to mark the solar eclipse of March 9, 2016.

The post Solar eclipse to unite science students first appeared on EarthSky.