When Comet ATLAS (C/2019 Y4) was discovered on December 28, 2019 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) it was a very dim magnitude +20 object however, once it’s orbit was calculated it was initially tagged as a “comet to watch” in 2020. Comets are fickle objects, and while the message was sent and received by the astronomical community, most astronomers (professional and amateur alike) knew the standard caveat that precedes such news. Comets are like cats. Predicting their behavior is a risky business.
Best described as dirty snowballs with highly elliptical orbits they typically blossom as they get closer to their parent star. This blossoming occurs when solar radiation causes the nucleus of the comet to sublimate forming a coma or shroud of gas and dust to form around the speeding comet. The closer the comet gets to the Sun usually the more material is spewed, and the classic “comet tail” forms trailing the icy body and always pointing away or perpendicular from the Sun.
In March Comet ATLAS began a fairly dramatic brightening as it ticked up close to +7th magnitude, which was still below naked-eye observation, but it excited astronomers, and ATLAS was all the buzz. ATLAS was perched fairly high in the north and made for a good target for astrophotographers. But this comet had an April Fool up its sleeve. Within the first week of April photographs showed a chunk breaking off the comet’s nucleus, it slipped in magnitude down below +9 and talk of total disintegration or a big breakup ensued dashing hopes of a strong naked-eye showing in late April and May. While a strong naked-eye showing is now diminished it’s not totally out of the question.
At this writing Comet ATLAS is gliding through the dim but large constellation Camelopardalis and is a circumpolar object. That means for most northern hemisphere dwellers the comet is always visible and doesn’t drop below the horizon. It’s currently at +9.2 magnitude. ATLAS is roughly 1.0 AU from Earth presently and will reach closest approach on May 23rd when it’s .78 AU from Earth.
Comet ATLAS C/2019 Y4 Printable Finder Chart courtesy of cometchasing.skyhound.com/
The question we all want to know is will it brighten back up or will it fizzle out? The answer is hard to say but with an orbital period of over 6000 years it’s safe to say this snowball has made a few trips around the Sun and with each inner solar system showing more material was lost. Could this be its last dance with Sol or is it possible that ATLAS has another surprise up it’s sleeve? My guess is Comet ATLAS is on its last leg but I’ll be happy to get that wrong in exchange for a strong showing over the next couple of months. Time will tell.
Clear Skies,
Scott