In a rare event for astronomers everywhere, “Atlas,” a huge comet roughly half the size of our sun, is predicted to appear brighter than Venus as seen from Earth by the end of April 2020. For stargazers, the appearance of Atlas may very well be the most exciting cosmic show to grace the night skies in years.
The comet was originally discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Hawaii, an automated sky survey that searches for potential Earth-crossing asteroids, on Dec. 28, 2019, Astronomy.com reported. The Atlas comet was named after the system itself.
As per Earth Sky, when the comet was first observed, it was faint and required a telescope to be seen. As of late March 2020, the comet is close to Mars’s orbit and shining at a brightness comparable to an 8th-magnitude star. As it continues to approach the inner solar system, it will become one of the brightest objects in the night sky.
To date, Atlas has increased in brightness 4,000-fold since the day of its initial discovery. Many experts predict that the comet will be bright enough to be seen with the naked eye, from dark sky locations, by the end of April.
“It’s definitely a promising comet,” Daniel Brown, an astronomy expert at Nottingham Trent University, told The Times. “It’s pushing towards a level that by the end of April could look really, really stunning.”
Astronomer Matthijs Burgmeijer predicted that the comet may even become “the brightest comet since records began.”
“How bright will it get?” Burgmeijer reflected, as per the Daily Mail. “The estimates are from a conservative magnitude +2 (visible to the naked eye) to a spectacular magnitude -11, which would make the comet the brightest comet since records began. We simply have to wait and see how it will develop over the coming weeks.”
Burgmeijer added an addendum; comets are notoriously unpredictable. Still, it is rapidly ballooning in size.
While the rocky, frozen core of the Atlas comet may only be a few miles in diameter, its atmosphere is humongous. According to Space Weather Archive, the gaseous atmosphere surrounding the comet has grown to an extraordinary 447,387 miles in diameter since December 2019.
For context, the Sun’s diameter registers as approximately 865,370 miles; the Earth’s is 7,917 miles.
According to Dr. Tony Phillips of Space Weather Archive, it’s not unusual for comets to grow to this size owing to the sheer volume of dust and gas that they expel along their journey.
Michael Jäger of Weißenkirchen, Austria, who captured a photograph of the growing comet on March 18, 2020, explained that Atlas’s newly formed tail was roughly the same diameter as its “coma,” or atmosphere. The comet’s tail certainly increases the chances of avid stargazers being able to see the comet in the night sky in the weeks approaching its closest position to Earth.
According to Earth Sky‘s reckoning, the Atlas comet is of no threat to Earth. Even at its closest distance to us, the comet will still be some 72.6 million miles away.
Another feature that will allow the comet to stand out among the many and varied constellations of the night sky is its distinctive green hue, which derives from diatomic carbon, a common constituent molecule in comets.
As per Space.com, gaseous diatomic carbon typically emits an ethereal green glow in the near-vacuum of space and has already made for the subject of some extraordinary astrophotography.
The Atlas comet continues to approach Earth, becoming increasingly visible each day. By late April, stargazers may no longer need their telescopes to spot the distinctive comet, and by late May, the comet is expected to rival Venus in brightness.
Astronomy.com predicts that the Atlas comet is billed to reach perihelion—its closest position to the Sun—on May 31 before making a sharp turn around our star on its onward journey on through the universe.