Space

Is bright Comet ATLAS disintegrating?

Two images: multicolored ovals with yellow centers. Center elongated in right image.
Images of Comet ATLAS – taken on April 5, 2020 – show an elongation of the comet’s nucleus. The elongation is aligned with the axis of the comet’s tail. Astronomers have seen before that comets exhibit this sort of elongation shortly before disintegrating. Image via astronomers Quanzhi Ye (University of Maryland) and Qicheng Zhang (Caltech)/ Ningbo Education Xinjiang Telescope.

Updated April 12, 2020.: The shattered heart of Comet C/2019 Y4 (ATLAS)

Updated April 11, 2020.

Recent observations of Comet C/2019 Y4 (ATLAS) show that it’s fading in brightness. According to observers’ reports, after gradually brightening to magnitude 8 as it crossed Mars’ orbit, the comet has appeared fainter during the last few nights. It has sunk to a magnitude of around 8.8 to 9.2 (the bigger the number, the fainter the sky object). Is Comet ATLAS disintegrating? Are our hopes for a bright comet – or even one visible to the eye – dashed? It appears so.

Astronomers Quanzhi Ye (University of Maryland) and Qicheng Zhang (Caltech) submitted an astronomical telegram titled Possible Disintegration of Comet C/2019 Y4 (ATLAS). According to their telegram:

We report the possible disintegration of comet C/2019 Y4 (ATLAS), revealed by the public monitoring program carried out by the 0.6-m Ningbo Education Xinjiang Telescope (NEXT). Images taken on UT 2020 April 5.6-5.9 showed an elongated pseudo-nucleus measuring about 3 arcsec in length and aligned with the axis of the tail, a morphology consistent with a sudden decline or cessation of dust production, as would be expected from a major disruption of the [comet’s] nucleus.

In the days following the original announcement, other observers also began reporting signs of disintegration:

Does this mean the end of Comet C/2019 Y4 (ATLAS)? Probably. However, time and time again, comets have shown themselves to be erratic and unpredictable. In case Comet ATLAS does remain visible – and in one piece – EarthSky shares some charts below to help you find the celestial visitor.

View at EarthSky Community Photos. | Photographer Steve Pauken in Bisbee, Arizona, said: “Comet C/2019-Y4 Atlas on April 2. Getting a bit brighter.”

Original article is below. Be aware that, if the comet has faded – as now appears likely – all bets are off for brightness predictions.

A recently discovered comet is getting the attention of astronomers and sky enthusiasts as it’s become brighter than expected in the last few days. Astronomers using the ATLAS (Asteroid Terrestrial-impact Last Alert System) in Hawaii discovered Comet C/2019 Y4 (ATLAS) on December 28, 2019. As of mid-late March, it shines at about the brightness of an 8th-magnitude star – not visible to the eye yet – but within reach of medium-sized telescopes in dark skies. The comet is currently crossing Mars’ orbit and is approaching the inner solar system. As it gets closer to us, it’ll get brighter still. You’ll find charts for observers at the bottom of this post.

Comet ATLAS should become bright enough to be easily visible in binoculars, and perhaps bright enough to be seen with the unaided eye from dark sky locations.

Just know that comets are notoriously erratic and inherently unpredictable! We will have to wait to see how Comet ATLAS performs.

Star field with one fuzzy elongated dot.
View at EarthSky Community Photos. | John Grage captured Comet ATLAS from Mind`s Eye Observatory in Sebastian, Florida, on March 28. He said: “This image was taken while performing first light with a new camera and doing my part for social distancing … something most amateur astronomers happily do nightly!” Thank you, John!
Fuzzy green object in dense starfield
View at EarthSky Community Photos. | Abhijit Patil captured Comet ATLAS on March 27, 2020, from near Killington, Vermont. He wrote: “The first comet I have ever seen or captured with a camera or naked eye. It was thrilling to see it and take a photo of it in my camera. All things learnt in school are coming to life with this hobby. Comet Atlas Y4 was discovered in Dec 2019. It is at a distance of approx 72 million miles from Earth at its closest approach. The nucleus of the comet is 10 km in diameter while the gases around it spread a few miles across. The comet is visible in the night sky in the North direction and can be seen through small telescopes. It is expected to brighten in the coming weeks. It should be visible to the unaided eye from dark sky sites.”
A fuzzy green little slightly oblong comet in front of the stars.
Steve Pauken in Bisbee, Arizona, caught this image of Comet C/2019 Y4 (ATLAS) on March 16. He wrote that the comet is: “… supposed to get brighter slowly until mid-May. Since no one else wants to sit in the cold evening air with me, it’s a great way to practice social distancing. :-)”
Black background with a few white dots and one large fuzzy green dot.
Another great image of Comet C/2019 Y4 (ATLAS), by Efrain Morales from Aguadilla, Puerto Rico. The marked object is a distant galaxy.

Astronomer Alessandro Marchini, director of the Astronomical Observatory at the University of Siena in Italy, sent the video below on March 21, the day after the death toll from COVID-19 in Italy had ramped up dramatically. He wrote:

During this surreal period of the health emergency for the Covid-19, I’m trying to use our social channels to entertain people forced at home. This evening I observed the comet C/2019 Y4 ATLAS during a Facebook Live streaming and here is a time-lapse I made with the images I acquired with our telescope. I hope all is fine with you.

Follow Osservatorio Astronomico Università di Siena on Facebook

Follow Osservatorio Astronomico Università di Siena on YouTube

Thank you, Alessandro, and please stay safe.

Comet C/2019 Y4 (ATLAS) will come closest to Earth on May 23, 2020. Its perihelion or closest approach to the sun will occur on May 31, 2020.

If predictions are correct, Comet ATLAS might reach a visual magnitude of +5 around May 1, 2020. That is theoretically bright enough to be see with the unaided eye, but the fuzziness of faint comets can make them harder to spot than comparably bright stars. When looking for fuzzy objects, it’s best to use averted vision: explanation here.

How bright will the comet get after that?  Estimates of Comet ATLAS’s peak brightness range from magnitude +2 to -6 during perihelion or closest approach to the sun, but please know that many comets fizzle and never reach their expected brightnesses. We will have to wait and see.

Concentric colored circles on a black background with one long parabolic curve cutting through them.
Orbit of Comet C/2019 Y4 (ATLAS). Image via NASA/ JPL.

How close to our planet will the comet come?  The celestial visitor will pass at a huge distance, at some 72,610,769 million miles away (116,855,706 km).

Comet C/2019 Y4 (ATLAS) will pass very close to the sun, and thus may disintegrate before becoming bright enough to be seen with the unaided eye.

It will pass at some 23,517,819 miles (37,848,261 km) from the sun, which is closer to our star than Mercury’s elliptical orbit (about 36 million miles or 57.9 million km on average).

Calculations by NASA/JPL indicate Comet ATLAS takes some 6,025 years to complete an orbit around the sun. Observations show it has a similar orbit to the Great Comet of 1844, which suggests that Comet ATLAS may be a fragment of the same 1844 comet.

Will Comet C/2019 Y4 (ATLAS) provide a good show or just fizzle out? Let’s keep a close eye on it, just in case! Bookmark this article, as we’ll provide updates and new photos when we can …

Here are some charts for you.

Star chart with Big Dipper and comet location.
Location of Comet C/2019 Y4 (ATLAS) in late March 2020. This chart faces north-northeast from a temperate latitude in the Northern Hemisphere. The time is around 9 p.m. local daylight (8 p.m. if you’re not using daylight time) for all locations. In late March, the comet requires a small or medium-sized telescope, but it may be visible in binoculars very soon! Illustration by Eddie Irizarry using Stellarium.
Star chart with North Star Polaris and Big Dipper and comet location.
Location of Comet C/2019 Y4 (ATLAS) during late March 2020. Facing north-northeast at around 9 p.m. local daylight time (8 p.m. if you’re not using daylight time) for all locations. In late March, the comet requires a small or medium-sized telescope, but it may be visible in binoculars very soon!  Illustration by Eddie Irizarry using Stellarium.
Star chart with Big Dipper, North Star Polaris, and location of comet.
Location of Comet C/2019 Y4 (ATLAS) during early April 2020. Facing north at around 9 p.m. local daylight time (around 8 p.m. if you’re not in daylight time). Illustration by Eddie Irizarry using Stellarium.
Star chart with Big Dipper, Venus, Capella and location of comet.
Location of Comet C/2019 Y4 (ATLAS) on April 15, 2020, around 9 p.m. local daylight time (around 8 p.m. if you’re not in daylight time). Illustration by Eddie Irizarry using Stellarium.
Star chart with Venus and Capella and location of comet.
Location of Comet C/2019 Y4 (ATLAS) on April 30, 2020, around 9:30 p.m. local daylight time (around 8:30 p.m. if you’re not in daylight time). Illustration by Eddie Irizarry using Stellarium.
Star chart with horizon, Venus, and Capella with location of comet.
By May 15, 2020, Comet C/2019 Y4 (ATLAS) will become increasingly closer to the northwest horizon. By then it might be bright enough to be easily seen with small binoculars, or perhaps even with the unaided eye! Illustration by Eddie Irizarry using Stellarium.

Bottom line: Recently discovered Comet C/2019 Y4 (ATLAS) appeared bright. Many hoped it would become bright enough to see with the eye alone. But in early April the comet began to fizzle.

Posted 
April 8, 2020
 in 
Space

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