Check out these Comet Nishimura photos from around the world.

Nishimura and the Sigma-Hydrid meteors

Comet C/2023 P1 (Nishimura) burst into our consciousness in August of 2023. It never got as bright as some hoped, but it still made a glorious target for astrophotographers. But is there still a chance to see parts of Comet Nishimura? Yes, only not as the comet itself, but instead as the dust it left behind in our atmosphere. Astronomers think Nishimura may be the parent comet of an annual meteor shower known as the Sigma-Hydrids. This minor annual shower is active each year between December 9 and 12. Scientists will be closely monitoring the shower this year to see if there’s an uptick in meteors. And it might be worth it for us to go out and look, too!

So, if Nishimura is indeed related to the Sigma-Hydrids, then the comet might have “refilled” its path with icy comet particles. While this is normally a very quiet shower, it might be more active this year.

The video below is from December 2022, taken in the Caribbean. It’s a Sigma-Hydrid meteor, a possible Nishimura-related meteor!

Videos of Nishimura

Professional observatories that peer at the sun have caught the comet in their images. You’ll find some amazing videos of the comet below.

Comet Nishimura – that great icy ball moving through space, which so many have captured on film – was closest to Earth on September 12. It was then closest to the sun (perihelion) on September 17.

Meanwhile, the comet is also expected to reappear in our dawn skies toward the end of 2023. But by then it’ll be too distant, and too dim, to view, as it sweeps farther away. But we may get to see some of what it left behind in December, however, with the Sigma-Hydrids meteor shower!

Wondering what happened to comet Nishimura? It's still quite happily sunbathing in the field of view of our @USNRL HI-1 camera on @NASA STEREO-A! Lots of great ion tail / solar wind interaction happening! ????

Download the full-res movie here: https://t.co/gkv2HCpIUS pic.twitter.com/xzHvdgBfjt

— Karl Battams (@SungrazerComets) September 26, 2023

The story of comet Nishimura

Hideo Nishimura of Kakegawa, Japan, was photographing the night sky on August 11 and 12, 2023, when he captured a new comet that now bears his name: comet C/2023 P1 (Nishimura). In fact, the comet was hiding in the sun’s glare before Nishimura picked it up in his images.

It continued to brighten as it closed in on the sun (perihelion was September 17). Later, after passing closest to Earth on September 12, it emerged low in the evening sky. Some saw it with binoculars in the western evening twilight.

A local comet

On September 1, 2023, NASA/ JPL made new orbital calculations that indicated that comet Nishimura orbits the sun every 435 years, which suggests this is a “local comet” from our solar system and not an interstellar comet.

Closest approach to Earth occurred on September 12, 2023, when the comet passed 78 million miles (125 million km) from Earth.

Perihelion – or closest approach to the sun – was on September 17, 2023, at 27 million miles (43 million km) from our star.

In fact, during perihelion, comet Nishimura passed closer to the sun than Mercury’s orbit.

Sightings of comet Nishimura

Comet Nishimura (C/2023 P1) on Sept 5, 2023. For this single shot I used my A7s and a 135mm lens.

Nishimura is a new comet that was discovered on August 11, 2023. It's expected to brighten to a magnitude of 1.8. Its closest approach to us will be on Sep 12 and its perihelion on… pic.twitter.com/BXhDo0IOpq

— Dr. Sebastian Voltmer (@SeVoSpace) September 6, 2023

comet C/2023 P1 (Nishimura) from Belfast, N Ireland at around 5am on 4th Sept 2023. Cropped from a 100mm image – stack of 50 x 3secs at ISO800. (Some problems with stacking caused a halo above neighbour's roof!) @martinastro2005 pic.twitter.com/jCuuZa3egN

— Philip?EcotrakNI (@EcotrakNI) September 4, 2023

comet C/2023 P1 (Nishimura): Such a strong solar wind. The disconnection event on September 2nd – the spectacular development in a 20-minute animation (RASA 11 QHY600) and 4x80sec red Michael Jäger pic.twitter.com/qf43YqhBbl

— Michael Jäger (@Komet123Jager) September 2, 2023

Bottom line: Comet Nishimura may be the parent comet to the Signma-Hydrid meteor shower, which peaks between December 9 and 12. Will the shower be more active this year? The only way to know is to go look!

See photos of comet Nishimura from the EarthSky community

Via:

NASA

Harvard

IAU Minor Planet Center

Star Walk

The post Comet Nishimura and the Sigma-Hydrid meteors first appeared on EarthSky.

Starship met a fiery end near Puerto Rico

After SpaceX launched its 2nd Starship test flight on November 18, 2023, the 1st stage exploded shortly after separation from the main spacecraft. That explosion occurred over the Gulf of Mexico. Astronomers, other experts, weather radar images, witnesses and videos all suggested Starship continued its flight toward the Caribbean for a few minutes. Then, around 8 minutes into the flight, Starship appeared to come to an explosive end, with a reentry just north of Puerto Rico and the U.S. Virgin Islands.

According to sighting reports, Starship disintegrated near Puerto Rico around 9:15-9:16 a.m. AST (13:15-13:16 UTC) on Saturday.

Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics said:

I infer an impact point in the Atlantic at about 13:19 UTC near 65W 19N, north of Puerto Rico and the U.S. Virgin Islands. Indeed, a debris cloud was detected in NOAA weather radar data at that time and location, confirming this analysis.

Marco Langbroek, a satellite and orbital tracking expert, also agrees that Starship appears to have reentered in the Caribbean:

(Trajectory) brings it near the debris trail north of Puerto Rico as observed by weather radar.

And NOAA/NWS radar detected a reentering debris field near Puerto Rico.

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Radar loop of debris field from NWS San Juan radar. pic.twitter.com/IdxzVCWty6

— AnthonyCarl8610 (@ACarl8610) November 18, 2023

Closeup of the breakup

Eyewitness reports

One of the witnesses, a sports photographer, was with camera in hand taking pictures of surfers at a beach in Dorado, Puerto Rico. Jankiel Carranza, of JCJ Photos, said:

I saw this blazing object falling from the sky from northwest to northeast. I took a picture probably near the end of the sighting, but the object was even brighter just a few seconds before.

Carranza was able to capture the reentry with a camera using a 70-300mm zoom lens. His picture is a remarkable one, because it clearly shows a disintegrating object with noticeable fragmentation, leaving smaller objects or debris behind, which is characteristic of a manmade object reentry, and not a natural object such as a space rock (meteor).

At last contact, Starship was still at a 92-mile (148-km) altitude and traveling at around 15,000 miles per hour (24,000 kph), probably with propulsion. This means that any trajectory deviation or altitude loss would cause it to disintegrate through the atmosphere while still showing a huge speed. This description coincides with the object seen in this video taken from Puerto Rico.

Angélica Pérez, another witness to the event, said:

The object showed noticeable fragmentation, leaving smaller pieces behind the main, bright and golden object.

Here’s another video from San Juan, Puerto Rico, by Elias Sobrino Najul.

Many people in Puerto Rico, Anguilla and British Virgin Islands reported that they heard an explosion-like sound, and even felt a rumble, around 9:16 a.m. AST, which coincides with the time of the Starship reentry over the Caribbean. This suggests a good\-sized mass of the object was reentering the atmosphere, and since Starship was covered with thermal protection tiles, it cannot be ruled out that some considerable debris might in fact have reached the surface (ocean) in the eastern Caribbean.

A view from the Florida Keys

Although some people initially thought that Starship’s second stage also exploded over the Gulf of Mexico, this image taken from the Florida Keys suggests the spacecraft, with fins visible, was still intact when passing by that area during its flight.

Please let me know if my tracking shot of the Starship debris from the Florida Keys after its explosion could be of any use to you, I'd be happy to provide the raw footage. pic.twitter.com/AmZ1vgNmaY

— Astronomy Live (@astroferg) November 19, 2023

Reentry maps

Bottom line: After the launch of Starship on November 18, 2023, the spaceship seems to have triggered its self-destruct mode around 8 minutes in. Witnesses around Puerto Rico saw what they believe to be its fiery reentry.

The post Eyewitnesses saw fiery Starship reentry over Caribbean first appeared on EarthSky.

Lost tool bag captured on video

The tool bag recently lost by NASA astronauts during a spacewalk is now orbiting Earth and is surprisingly visible to stargazers. The object can appear as bright as a 6th-magnitude star. You can see it in the video above by Eddie Irizzary and Nelson Ortega taken from Añasco, Puerto Rico, on November 11, 2023, around 7:15 pm AST (23:15 UTC). At the time, the tool bag was passing close to where we see Delta Aquilae and Altair, the brightest star in the constellation Aquila the Eagle. Orbital tracking and predictions confirm the object in this video is, in fact, the tool bag that astronauts Jasmin Moghbeli and Loral O’Hara accidentally lost on November 2, 2023.

The tool bag changes slightly in brightness, suggesting the object is tumbling as it orbits our planet. Although the tool bag was ahead of the International Space Station (ISS) by about a minute or two shortly after the incident, it is gradually appearing farther ahead of the ISS as it loses altitude.

In fact, it was already about five minutes ahead of the ISS on November 11 (the date the video was taken). By mid-November, the tool bag should be ahead by about ten minutes.

Observations also indicate that as the tool bag loses altitude, it has drifted slightly to the east, or left, of the ISS’s trajectory.

In the last segment of the video above, the ISS appears. It was passing close to where we see the bright star Altair.

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How long will it be up there?

The tool bag should remain in orbit around Earth for a few months yet. Unlike the ISS, the tool bag will rapidly descend in orbit until it reaches about 70 miles (113 km). At that point it will disintegrate. New estimates indicate the tool bag should reenter the atmosphere between March and July of 2024.

How to see the tool bag with binoculars

It’s surprisingly bright (for a tool bag), shining just below the limit of visibility to the unaided eye at around magnitude +6. That means some sky observers should be able to pick it up with binoculars.

The first step to seeing it is checking if you have a visible pass of the ISS. Check here for how to see ISS in your sky. Your strategy will be to figure out the trajectory of the ISS and look for it before the space station crosses the sky. It’s already five minutes ahead of the ISS and will soon be nearly 10 minutes ahead.

If you get an image, please submit it to EarthSky Community Photos!

How did it get lost?

The spacewalkers were conducting repairs on assemblies that allow the ISS solar arrays to track the sun continuously. A blog post at SciTechDaily, which was describing the spacewalk, explained:

During the activity, one tool bag was inadvertently lost. Flight controllers spotted the tool bag using external station cameras. The tools were not needed for the remainder of the spacewalk. Mission Control analyzed the bag’s trajectory and determined that risk of recontacting the station is low and that the onboard crew and space station are safe with no action required.

The lost tool bag on social media

Last seen by @Astro_Satoshi while floating over Mount Fuji ? the 'Orbital Police' can confirm that the lost EVA gear is being tracked ? https://t.co/wz4MITmAfM pic.twitter.com/eksfu9fPFw

— Dr Meganne Christian (@astro_meganne) November 5, 2023

A tool bag was lost during last week’s EVA to replace a trundle bearing on the port solar alpha array. The object is now listed in the catalog as ID 1998-067WC/58229. The tool bag as a +6th magnitude ‘star’ currently about a minute ahead of the ISS.https://t.co/2YZf3PnjzV

— Dave Dickinson (@Astroguyz) November 6, 2023

The crew lock bag that floated free during the Nov 1 EVA-89 spacewalk has been cataloged as 58229 / 1998-067WC in a 415 x 416 km orbit

— Jonathan McDowell (@planet4589) November 5, 2023

Not the first time

And this isn’t the first time a NASA astronaut has lost a tool bag. On November 18, 2008, astronaut Heide Stefanyshyn-Piper was performing a similar repair at the ISS when she inadvertently lost a tool bag.

Some two months later, on January 12, 2009, the object was still visible ahead of ISS and was seen with binoculars by Joxelle Velazquez among others during a star party at Cabo Rojo, Puerto Rico. See the image below.

There’ve been earlier losses of astronauts’ items, too, to the junkyard of near-Earth orbit. Victor Tangermann at Futurism reported on November 3:

It’s far from the first time astronauts have lost track of tools in space. Back in 1965, NASA astronaut Ed White infamously lost a spare glove during a spacewalk outside of his Gemini 4 spacecraft. Over the decades, several other astronauts have lost other objects, from spare bolts in 2006 to an entire bag ironically containing a debris shield in 2017.

And, although NASA has determined that the 2023 tool bag isn’t on a trajectory that’s dangerous to the astronauts aboard the ISS at this time, the problem of litter in near-Earth orbit remains and is serious. As Tangermann wrote at Futurism:

The problem, of course, is that not every piece of space debris will stay out of the way of future space travelers.

And that is a sad truth.

Bottom line: NASA astronauts accidentally lost a tool bag during a spacewalk on November 2. Now, observers on the ground have caught the tool bag on video. See it here.

Via SciTechDaily

The post Lost tool bag from spacewalk caught on video first appeared on EarthSky.

Seeing sunspots during a solar eclipse

Millions will cast their (protected) eyes toward the sun during tomorrow’s solar eclipse. While only those on the path of annularity will be able to see the ring of fire – the outermost layer of the sun in a ring around the moon at mid-eclipse – almost all of North America, and much of South America, will see a partial eclipse. Here’s something fun to try while you’re waiting for maximum eclipse. As the moon is passing in front of the sun, look for sunspots on the unblocked portion of the sun’s surface. Most sunspots are too small to see with ordinary eclipse glasses. But your eclipse glasses will show you a large sunspot. And there’s a good-sized spot near the sun’s east limb now that you can at least try for.

Plus many observers will be watching the eclipse using indirect viewing, or telescopes and binoculars, with special solar filters. No matter how you’re viewing, look at the sun carefully. Do you see any dark spots?

The good news is that the emerging sunspot – labeled AR3465 – will become easier to see from Earth as the sun rotates. So the view on eclipse day (October 14) should be even better than that in the chart at the top of this post.

On this Saturday, as the eclipses progress, observers with solar telescopes will be able to see the moon’s black silhouette reaching and even covering some of the visible sunspots.

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Sunspots are fun

Sunspots are fun to see and contemplate. They are regions of strong magnetic fields on the sun’s surface. They appear dark because they’re cooler (or, perhaps more accurately, less hot) than other parts of the sun’s surface.

An amazing fact is that these dark patches may appear small to you, but they’re usually are a couple of times bigger than Earth’s diameter!

As the images above show, there will be likely be multiple spots on the face of the sun during the October 14, 2023, eclipse. After all, we’re moving toward the peak of the sun’s 11-year cycle of activity. So, on any given day, the sun has spots. The peak of this cycle – known as Cycle 25 – is predicted for the mid-2020s. Sunspots come and go. But they typically last on the order of several earthly days. So the sunspots we’re seeing on the east (left) side of the sun today (October 12) should still be mostly visible during the October 14 eclipse.

Sunspots sometimes emerge into the middle of the sun’s bright disk, too. In other words, they can surprise us! And those that do come into view on the east side of the sun – the side rotating into view of Earth – typically take about 12 days to move across the sun’s visible face, before turning the corner to the sun’s far side.

Sunspots viewed from Mars

The large sunspot in the east (by the arrow in the top image) is one of a few that earthlings have seen recently from another planet. NASA’s Perseverance rover – one of the active rovers currently making its way across the surface of Mars – has a solar filter as part of a filter wheel attached to its mast cameras.

The Perseverance rover on Mars has a different perspective on the sun than we do. That’s because Mars and Earth are currently on nearly opposite sides of the sun from each other. So Mars gets a peek of the activity that’s on the far side of the sun from Earth.

Some thoughts about telescopic filters

Of course, you don’t need to wait for an eclipse to view sunspots. You can view them whenever they’re visible on the sun (and again they’re going to be very visible over the next few years, as we reach solar maximum) … assuming you’re using protective filters.

The most popular and affordable solar filters for telescopes are the white light filters, which provide nice views of sunspots. Some with higher resolution will clearly show other features on the sun’s surface, including faculae – bright areas with a white appearance – which are also magnetically strong fields, although less concentrated than in sunspots.

Hydrogen alpha filters or Ha telescopes, while more expensive, show amazing views of solar prominences that look like flames on the sun’s edge. Those will also provide a nice twist to the solar eclipse, showing the moon’s dark disk close to the prominences.

If you didn’t pick up a solar filter or a pair of solar binoculars in time for this eclipse, there’s another one on the way for North America! Plan now and you can be stocked up in time for the total solar eclipse on April 8, 2024.

Bottom line: If you’re watching the annular or partial solar eclipse on October 14, 2023, with safe filters, look for sunspots around the disk of the dark moon.

The post Seeing sunspots during the solar eclipse on October 14 first appeared on EarthSky.

Starlink satellite disintegrates over the Caribbean

Witnesses in Puerto Rico and the Dominican Republic saw a spectacular satellite reentry around 7:25 p.m. local time (23:25 UTC) on September 6, 2023. Observers reported the reentry appeared across the sky from horizon to horizon, blazing a path from southwest to northeast. According to reentry predictions, the object was Starlink-30167, a satellite from SpaceX’s Starlink constellation, launched on July 28, 2023. Although the new Starlinks are called “V2 mini”, when the solar panels are deployed each spacecraft is 100 feet (30 m) wide.

The time and location of the reentering Starlink satellite was confirmed by various organizations that monitor decaying objects in orbit.

The Starlink-30167 was part of a group of 22 internet satellites launched on a Falcon 9 rocket from Florida’s Cape Canaveral Space Force Station. However, this particular satellite failed to reach its intended orbit. It gradually lost altitude and eventually reentered Earth’s atmosphere.

How to tell a meteor from space debris

Although some observers may think at first they are seeing a meteor, there are two main characteristics that will let you know if it’s space debris.

1. Space debris appears as an extremely slow “meteor”, sometimes lasting one or two minutes. A natural meteor (space rock) takes just a few seconds to zip across the sky. In fact, space debris appears so slow that some people are able to turn on their phone’s cameras to take pictures or video of the event.
2. Another clear indication that the observed object is space debris in our atmosphere is that it will have a very noticeable fragmentation. You’ll be able to see some small objects separating from the main object, with some leading the main event while other fragments fall behind.

This is not the first time observers have seen Starlink satellites disintegrating in our skies. On February 7, 2022, a group of just-launched satellites reentered the atmosphere when a geomagnetic storm from the sun prevented the satellites from reaching their intended orbit. Geomagnetic storms cause the atmosphere to warm and affect atmospheric density, increasing drag and causing low-altitude satellites to reenter.

Bottom line: Watch as a Starlink satellite disintegrates on video over the Caribbean on September 6, 2023. See 3 angles of the satellite burning up here.

Via Aerospace

The post Starlink satellite disintegrates over the Caribbean first appeared on EarthSky.

Yet another newly discovered space rock safely zipped past Earth, this one on March 25, 2023. It swept by at about half the Earth-moon distance. Astronomers at the observatory of La Palma, in the Canary Islands, Spain, discovered the asteroid in late February 2023. And amateur astronomers were able to get a glimpse of the asteroid as it sped past. See the charts at the bottom of this post.

Closest approach to Earth was around 19:51 UTC (3:51 p.m. EDT) on March 25.

Apollo-type asteroid #2023DZ2. Diameter 39-87m. First observed at La Palma: 27th Feb' Close approach today. Distance 175,000 km from Earth. #SpotTheAsteroid #IAWN #QHY42Pro @QHYCCD @RoyalAstroSoc @skyatnightmag @SPACEdotcom @esaoperations @AsteroidWatch pic.twitter.com/O95YXuxFKr

— Northolt Branch Obs (@NBObservatories) March 25, 2023

The asteroid has been labeled 2023 DZ2. It’s part of the Apollo family of asteroids. Estimates put 2023 DZ2’s size at about 210 feet (64 meters) in diameter.

For comparison, the asteroid that entered over Chelyabinsk, Russia, in February 2013 was a space rock around 65 feet (20 meters) in diameter. Watch a video of size comparisons in asteroids here.

2023 DZ2 is classified as a NEO (Near Earth Object). It orbits the sun every 3.16 years.

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No risk of impact in 2026

For a while, this new asteroid posed a very slight risk of impact with Earth on March 27, 2026. Fortunately, as of March 21, 2023, officials have removed it from the Sentry Risk Table, saying they are:

…able to rule out previous potential impacts as no longer consistent with the observations.

?Astronomers with the International Asteroid Warning Network are using this close approach to learn as much as possible about 2023 DZ2 in a short time period – good practice for #PlanetaryDefense in the future if a potential asteroid threat were ever discovered.

— NASA Asteroid Watch (@AsteroidWatch) March 21, 2023

Visible in small telescopes

Asteroid 2023 DZ2 passed 0.5 lunar distances (half the Earth-moon distance) from Earth’s surface. The relative closeness enabled observers to see the space rock in six-inch (15-cm) and larger diameter telescopes.

The space rock was traveling at a speed of 17,403 miles per hour (28,008 km/h), or 7.78 km per second, relative to Earth. While it sounds like a huge speed relative to what we’re familiar with on Earth, it wa a relatively slow asteroid in contrast to other space rocks that astronomers study.

Since the asteroid passed at half the Earth-moon distance, the small distance made it appear as a “slow-moving star” in the field of a small telescope.

One of the best techniques sky enthusiasts use to catch an asteroid, is to point the telescope at a known star in the asteroid’s path. Then they just wait for the slowly moving space rock to appear. Fortunately, many small telescopes now include a computerized Go-To hand control. Thus, you can point the instrument at a reference star to get a glimpse of passing asteroids.

When was the best time to see asteroid 2023 DZ2?

We found the best time to see asteroid 2023 DZ2 from the Northern Hemisphere was early on the night of Friday, March 24, 2023.

Bottom line: Asteroid 2023 DZ2 safely passed Earth at less than half the distance between the moon and Earth on March 24-25, 2023. People with telescopes were able to spot the visitor.

The post 200-foot asteroid 2023 DZ2 passed closer than moon first appeared on EarthSky.

Astronomers have found a new comet! They’ve labeled it C/2023 A3 (Tsuchinshan-ATLAS). And it’s something to look forward to, as it makes its closest approach to the sun (its perihelion) more than a year from now. So, the bad news is it’s not until 2024. But the good news is that early estimates of the comet’s brightness suggest it’ll be bright.

Perihelion for this comet will come on September 28, 2024. At that point, some estimates are suggesting it might be around magnitude 0.7. That brightness rivals some of the brightest stars in the sky (though, for comets, the brightness is diffuse, not in a single point).

And of course, as with all comets, be aware that they are finicky balls of ice and dust, often not living up to expectations.

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Discovery and naming

The Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in South Africa discovered Comet C/2023 A3 on February 22, 2023. Additionally, observers at Purple Mountain (Zijin Shin or Tsuchinshan) Observatory in China found the comet independently on images from January 9, 2023. Therefore, the comet also has the nickname Tsuchinshan-ATLAS.

At discovery, the comet was still 7.3 astronomical units (AU) from the sun, and shining at a dim magnitude 18.

Where’s the comet now?

Preliminary analysis of its trajectory suggests comet “A3” completes an orbit around the sun every 80,660 years. As of March 2023, the celestial visitor is currently between the orbits of Saturn and Jupiter. Although some specific facts and dates might be updated, currently it appears that closest approach to Earth should occur on October 13, 2024 at 05:38 UTC.

An amazing detail of comet “A3” is its blazing speed: 180,610 miles per hour (290,664 km/h) or 80.74 km per second, relative to Earth.

When does the fun begin?

Amateur astrophotographers in the Northern Hemisphere may start getting good images of the approaching comet by early June 2024, as the visitor glides by the constellation of Virgo. The comet gets lost in the glare of the sun by August 2024. Then it passes at perihelion – or closest to the sun – on September 28, 2024. Observers with an unobstructed view of the eastern horizon might get a view of the comet during perihelium, especially if the visitor develops an impressive tail.

The development of a nice tail is a possibility, because the comet will be a lot closer to the sun than the planet Venus. In fact, it will be so close to our star that during perihelion, comet A3 will be skimming the orbit of planet Mercury. However, this closeness to our star comes with a known risk for comets; the possibility of disintegration. That’s the reason why there is a current debate on whether this comet will or will not survive its approach to the sun.

If comet A3 survives perihelion, it’ll be too close to the eastern horizon during its closest approach to Earth. The good news is that the high speed of the comet will get it higher in the sky during the following nights after passing by our planet, thus making it easier to spot in the western sky.

Closest approach to Earth

Its closest approach to Earth comes on October 13, 2024. At that point, it could be bright enough to reach magnitude -0.2. As it passes between Earth and the sun, forward scattering could make the comet appear even brighter. The reflection of sunlight off the dust and ice could enhance its light in our direction, making it brighten considerably, up to magnitude -5. That is, if it survives.

We know very little about the *properties* of comet C/2023 A3 (Tsuchinshan-ATLAS), so the assessment in https://t.co/NZF4hEF5hj is important: the "conditions are extremely favorable" but it could also "have a sub-kilometer nucleus that disintegrates leaving us nothing to see" …

— Daniel Fischer @cosmos4u@scicomm.xyz (@cosmos4u) March 1, 2023

The path of Comet C/2023 A3

After the comet gets closest to the sun, it will swing around near Earth. But as it does so, it passes almost directly between Earth and the sun, making it challenging to view. In early October, the comet will be in the dawn sky in Leo and near the constellations Hydra and Crater.

Then in late October, as it appears on the other side of the sun, it will move into the evening sky, passing through Serpens Caput and into Ophiuchus.

Finder charts for C/2023 A3

Bottom line: A newly discovered comet, C/2023 A3 (Tsuchinshan-ATLAS), could be quite bright in October 2024.

The post New comet – C/2023 A3 – could be bright in 2024 first appeared on EarthSky.

Asteroid will pass Earth safely this week

Yet another asteroid in the news! This one is a little less splashy than the recent disintegration of the one-meter-wide asteroid over France. But it’s this asteroid’s closest approach to Earth in more than 400 years. And the asteroid is medium-sized, about half a mile (about 1 km) wide. This asteroid – which is called 199145, or 2005 YY128 – is set to safely pass by our planet on the night of Wednesday, February 15, 2023.

And observers with telescopes can watch it. In fact, on recent nights, amateur astronomers using telescopes have already been able to spot this space rock. And astronomers using the Goldstone Antenna in California tried to obtain radar images of asteroid 2005 YY128 from February 11 to 13, 2023. If they succeeded, and we run across any of those images, we’ll add them to this post.

About the name 2005 YY128. The 2005 indicates the year of discovery. Astronomers at Kitt Peak Observatory in Tucson, Arizona, discovered asteroid 2005 YY128 on December 30, 2005. And so the orbit of this asteroid has been tracked for years, and is well known.

That’s why we know there’s nothing to fear from this asteroid. Based on studies of its movement through space, astronomers have determined it will safely pass by our planet’s south pole at about 12 times the moon’s distance.

Its closest approach to Earth will happen on February 15, 2023, around 7:46 p.m. EST.

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Asteroid 2005 YY128 from the Southern Hemisphere

This asteroid is passing to the south of Earth. And observers in the southern U.S. had a shot at spotting the space rock using small telescopes on the night of February 13.

Meanwhile, those in the Southern Hemisphere will be favored with possible views during the asteroid’s closest approach.

The path of the asteroid

The Apollo-type asteroid is traveling through space at a speed of 55,140 miles per hour (88,740 km/h or 24.65 km/sec), relative to Earth. The space rock’s high speed allows amateur astronomers to detect its motion in front of the stars. But the distance makes it appear as a slow-moving object.

This video shows asteroid 2005 YY128, which appears as a small moving star. Raymond Negron captured the asteroid with a 92-mm telescope from Cabo Rojo, Puerto Rico:

What is a Potentially Hazardous Asteroid?

Astronomers categorize asteroids as potentially hazardous if their orbits and brightnesses (an asteroid’s brightness suggests its size) meets certain parameters. So potentially hazardous doesn’t mean an asteroid is a true hazard to Earth at this time.

Instead, Potentially Hazardous Asteroids (PHAs) include all asteroids whose orbits carry them, at times, within of 0.05 AU (0.05 Earth-sun distances) or less of Earth. That’s 4,600,000 miles (7,402,982 km, or about 18 times the moon’s distance). They also must have at least this brightness – an absolute magnitude of 22 or brighter – to be considered PHAs.

With a diameter between 1,903 feet (580 meters) to 4,265 feet (1.3 km), the space rock 2005 YY128 earned the classification of a Potentially Hazardous Asteroid. 

What does that mean for us? Mainly that its medium size and relative closeness makes it bright enough for observers with an 8-inch or larger telescope to spot it. And sky enthusiasts with camera-equipped scopes have been able to capture the asteroid even in smaller telescopes.

Bottom line: A half a mile wide (1 km wide) asteroid will pass Earth safely on February 15 and 16, 2023. Observers with telescopes can spot it. See star charts here.

The post Asteroid will pass Earth safely on February 15-16 first appeared on EarthSky.

Show your sweetie the green comet

Okay, it’s not bright. And you’ll need a little patience and a dark-sky site to see it. Plus you’ll need binoculars, at least. But the comet is in a good place to try to see on this Valentine’s Day, 2023. Tonight and tomorrow night, those using optical aid can spot the green comet (C/2022 E3 ZTF) near the orange star Aldebaran, in the constellation Taurus the Bull. The green comet is dimming as it speeds out of the inner solar system. Catch it before it’s gone.

Astrophotographers can point a camera toward its approximate location in the sky and take long-exposure photos of 20 to 30 seconds. Your images might reveal a fuzzy, tailed object. Indeed, using this technique, many have been able to photograph a comet even if they can’t see it visually. Did you get a photo of Aldebaran and the comet? You can submit it to our EarthSky Community Photo page!

Current estimates of the comet’s brightness show that it should be shining around magnitude 6.5 by mid-February. That’s beyond the limit of visibility to the unaided eye. If you want to see it with your own eyes, you’ll need binoculars, or a small telescope, and a dark-sky site.

The moon will rise after midnight local time on February 14, leaving a small window for viewing. Be aware that the comet sets around 1 a.m. local time (the time on your clock, no matter where you are on the globe).

The 2023 EarthSky lunar calendar is on sale! A unique and beautiful poster-sized calendar showing phases of the moon every night of the year. Treat yourself!

How to see the comet

Use the star charts here to track down the comet. Its northern location on our sky’s dome means Southern Hemisphere stargazers don’t have a good view of this comet. For them, the body of Earth will block it from view. Be sure to check Stellarium for a precise view from your location, at the time you want to watch.

The comet is dimming as it leaves the solar system, but observers are still picking it out with binoculars. Look for a faint smudge. It won’t be a bright point, like a star. Instead, it will look like a spot that is just a bit lighter gray than the surrounding background of space. It can help to use averted vision to spot it.

Comet C/2022 E3 map for February

The comet was closest to Earth on February 1 and 2

On February 1 and 2, 2023, Comet C/2022 E3 (ZTF) reached its closest point to Earth. That’s when it passed 27 million miles away (that’s 44 million km, or 0.29 AU). At that point, it was still more than 100 times the moon’s distance away.

The last time this comet passed near the sun was 50,000 years ago, when Neanderthals walked the Earth. Now, as the comet returns to the outer solar system, we can enjoy what could be the brightest comet of 2023 before it gets too dim to see.

And don’t miss the photo gallery of the comet at the end of this post. Plus you’ll find more images of the comet here.

Good geometry

Comet C/2022 E3 (ZTF) has favorable geometry with respect to Earth. Normally, a comet will pass near the sun’s vicinity, and the elongation, which is the angle in degrees between the sun and the comet as seen from Earth, grows small and the comet disappears in the sun’s glare for a few weeks. Not this one, though! In contrast, it stays in the dark sky for most of its trip through the inner solar system.

Moreover, the tilt of the orbit relative to our path around the sun is steep and retrograde, meaning the comet goes around the sun in the opposite direction than do the planets. As a result, this means it will, at some point, move quickly through our sky. 

To begin with, the comet entered our solar system from the north, and on February 12, 2023, passes to the south of our orbital plane.

Northern Hemisphere observers will have a view of the comet until the end of April 2023, when the comet, then a telescopic object, will disappear into the evening twilight.

Southern Hemisphere observers, however, lost their view of the comet in early October 2022. It disappeared into evening twilight as it rapidly headed northward. Subsequently, their next view of the comet will come in early February 2023, when it pops above their northern horizon.

Green comet photos and videos: Editors’ picks

How Comet C/2022 E3 (ZTF) got its name

Astronomers discovered Comet C/2022 E3 (ZTF) using the 48-inch (1.2-meter) Samuel Oschin robotic telescope, part of the Zwicky Transient Facility (ZTF), located at Mt. Palomar in southern California. They discovered it on March 2, 2022, and it was the third such object discovered in the fifth half-month (A, B, C, D, E) of the year. Thus, 2022 E3 (ZTF).

The discovery story

Comet C/2022 E3 (ZTF) was in the morning sky, in the direction of the constellation Aquila the Eagle, when astronomers with the Zwicky Transient Facility first spotted it. 

The ZTF program images the whole Northern Hemisphere every two nights looking for supernovae, variable stars, binary stars, flashing merging neutron stars, asteroids and comets. Overall, it has discovered 10 comets in the past three years, and half of them carry the acronym ZTF in their names. One, discovered a year ago, was named C/2021 E3 (ZTF). Similar name, to be sure, but don’t confuse the two comets. Now, we are talking about the 2022 one!

A faint comet

At its March 2022 discovery, this comet had a very faint 17th magnitude brightness. Initially, it appeared as a stellar object, that is, as a dimly shining point. But, unlike the stars, whose distances make their motions undetectable except via special techniques, this object was moving in front of the stars.

Confirming its cometary nature

Furthermore, newly discovered objects found to be moving go into the Minor Planet Center’s NEO Page. That’s how other astronomers know what to image and hopefully, thereby, to confirm the object. Now, as both professional and amateur astronomers do find the new object, they submit more positions for it to the Minor Planet Center. Then, scientists can determine a preliminary orbit. In this case, it originally looked more like a comet’s orbit than an asteroid’s orbit. That is, the path around the sun was oblong and not circular. 

At that point, the object went on the Possible Comet Confirmation Page. Astronomers tried to image it to see if it had a coma or extended atmosphere surrounding the object’s nucleus or core. Why is that important? Basically, it’s important because, virtually, all asteroids – which tend to be rocky or metallic – appear starlike (the name asteroid means “starlike”) from Earth. But an icy comet will form a halo, or coma, around its nucleus as the material on the nucleus heats up when the comet is moving inward toward the sun. Indeed, only several high-magnification images, stacked to increase contrast, will show the coma of a faint comet.

In this case, three teams imaged this new object, and they did find a coma. 

Photos of Comet E3

Bottom line: The green comet – Comet 2022 E3 (ZTF) – will pass near the bright star Aldebaran – in mid-February. Here’s how to see them.

Submit your comet images to EarthSky Community Photos

Green comet photos and video: Editors’ picks

The post Green comet passes Aldebaran on February 14 and 15 first appeared on EarthSky.

Comet C/2017 K2 (PanSTARRS)

Hey, Southern Hemisphere observers, this one’s for you! Comet C/2017 K2 (PanSTARRS) is making its closest approach to the sun – called perihelion – on December 19, 2022. And you have to be south on the globe to spot it. The comet is currently near the border of the constellation Ara the Altar and heading into Pavo the Peacock. Reports show the comet around magnitude 8.5, which means you’ll want good binoculars and dark skies to see it.

The comet’s close approach to Earth was back on July 14, 2022, in northern skies. But the comet continues to head deeper into southern skies, making this observing target the domain of the 12% of Earth’s population that lives in the Southern Hemisphere.

Available now! 2023 EarthSky lunar calendar. A unique and beautiful poster-sized calendar showing phases of the moon every night of the year! And it makes a great gift.

How to see C/2017 K2

The website The Sky Live will help you spot the comet. You can find star maps there from the viewpoint of your location. Then you can locate the comet as it shifts among the constellations.

So, how do you go about seeing it? First, you’ll want to be under southern skies. Next, find a dark-sky site. Then, use binoculars or a small telescope to track down the comet.

You should see comet K2 as a fuzzy patch of light. The fuzziness is mostly the comet’s gigantic outer atmosphere, or coma. That coma is about 80,700 miles (129,900 km), which is 10 times the Earth’s diameter! And as the comet sweeps closest to the sun, the tail should appear longer than it did when it was farther away. Long-exposure images should reveal the comet and its tail in all its glory.

Astronomers estimate that Comet C/2017 K2 (PanSTARRS) has been traveling from the Oort cloud for some 3 million years in a hyperbolic orbit. 

The comet’s backstory

Astronomers first spotted the comet in 2017 using the Pan-STARRS survey instrument in Hawaii. At the time, they said it was the farthest active inbound comet they’d yet seen. It was located between the orbits of Saturn and Uranus when they first saw it.

Comets are mostly rock and ice. They become active when warmed by the sun. However, this comet was already active in 2017. The Hubble Space Telescope took an image of the comet looking like a fuzzy snowball while it was still in the outer solar system. The comet appears to have a large nucleus, and it shows a huge cometary atmosphere or coma.

PanSTARRS

If the name Comet PanSTARRS rings a bell, that’s because there are many of them. Pan-STARRS is a sky survey that is particularly good at spotting new asteroids, comets, supernovae and the like. This is Comet C/2017 K2 (PanSTARRS). At its discovery, K2 was 1.49 billion miles (2.4 billion km) from the sun. That’s 16 times farther away than the Earth is from the sun.

And if the name K2 reminds you of the second largest mountain on Earth, also named K2, keep in mind that the mountain is 28,251 feet (8,611 meters) tall. If the comet K2 is around 11 miles or 18 km (a reasonable estimate), that translates to about 58,000 feet or 18,000 meters. In other words, the comet K2 dwarfs the mountain K2, which is about half its size.

By the way, the new title-holder for farthest active comet is Comet Bernardinelli-Bernstein. Astronomers spotted this behemoth comet about 100 times the size of a normal comet. That’s when it was more than 2.7 billion miles (4.4 billion km) from the sun. Comet “Bern-Bern” will have its closest approach on January 21, 2031. But you have nothing to fear from it, as it will be slightly farther away than Saturn’s orbit.

Almost as big as Jupiter

Another indication that suggests C/2017 K2 is large, or at least very active, is that observations showed it developed a cometary atmosphere, or coma, with a diameter of about 81,000 miles (130,000 km). That would mean this comet’s coma is a sphere of gases 10 times the diameter of planet Earth, or almost as big as the diameter of planet Jupiter. That’s huge!

Also, some early observations detected an incredibly large tail, some 500,000 miles (800,000 km) long.

Scientists think that comets that are too far from the sun shouldn’t sublimate huge amounts of ice. So this comet’s activity is probably driven by a mix of ices with substances like nitrogen, carbon dioxide, carbon monoxide and molecular oxygen.

Most comets have a nucleus of about 0.5 to 2 miles (1 to 3 km) in diameter, while others may be up to 10 miles (16 km) wide. However, a few are really huge, including Hale-Bopp (37 miles or 60 km), Bernardinelli-Bernstein (93 miles or 150 km) and 95P/Chiron, also known as 2060 Chiron) at 124 miles or 200 km. In fact, 95P/Chiron may be a dwarf planet. However, it showed cometary behavior and thus got a comet designation.

When will we see the next bright comet?

Comet C/2022 E3 (ZTF) is expected to be as bright as magnitude 5 in January 2023. After that, the next possible good one appears to be comet 12P/Pons-Brooks, which might reach magnitude 5 or 4 in March 2024.

Comet C/2017 K2 images since closest approach to Earth

Images of Comet PanSTARRS before closest approach to Earth

Bottom line: Comet C/2017 K2 (PanSTARRS) reaches its closest point to the sun – perihelion – on December 19, 2022. It’s now a target for southern skies.

The post Comet C/2017 K2 is closest to the sun Dec 19 first appeared on EarthSky.