Tech & Science

Comet ASAS-SN1: Here's Your Chance to See a Comet That Won't Be Visible for Thousands of Years

This comet, called ISON, was first discovered in 2012. NASA

Updated | Sometimes in life you get lucky and find precisely what you were looking for—and other times you accidentally stumble upon a comet during your search for exploding stars.

That's what happened at the All-Sky Automated Survey for Supernovae this July, when it spotted what's now known as C/2017 O1, nicknamed O1 ASAS-SN or ASASSN after the network of eight instruments that discovered it.

Next week, O1 ASAS-SN is passing closer to Earth than the sun is, but don't worry; it will stay almost 67 million miles away. The comet is bright enough that for most of this month, you should be able to see it with a small telescope or a good pair of binoculars. Be aware that it will look blurrier than a star does (you'll know you're onto something if you have trouble convincing your binoculars to focus on it), and it may also show a greenish tinge, according to

Scientists don't know yet how large O1 ASAS-SN is, but the cloud of gas and dust around it that makes it look so fuzzy is more than 93,000 miles across.

The comet has also caused a bit of a political stir, with the astronomers who discovered it saying that the International Astronomical Union, which oversees the official names of everything in space, had declined to include the acronym of the discovering instruments in the comet's name. Space aficionado news site Universe Today suspects the reluctance may be due to the uncanny similarity of the acronym to the word assassin. 

Comets, which NASA colorfully refers to as "dirty snowballs of leftovers from the beginning of our solar system," fly into our celestial neighborhood on occasion from the Oort Cloud that circles the outer edges of the solar system. O1 ASAS-SN is brighter than many comets, which primarily shine with reflected sunlight. Earlier this summer, scientists realized there are seven times more comets with very long orbital periods, like O1 ASAS-SN, than they had previously assumed.

Throughout October, O1 ASAS-SN is slipping its way between the constellations Auriga and Perseus and approaching the Giraffe (all these constellations are visible from the Northern Hemisphere). recommends that viewers hoping to catch a glimpse of it flee city lights and aim for between October 13 and 26, when the sky will be darker. The few nights after the new moon on October 19 will also be the best time to catch the Orionid meteor showers, so there's even more reason to head outside.

If you want to see O1 ASAS-SN, don't miss this chance. It won't swing by Earth again for thousands of years—according to one calculation, not until the 57th century.

This article has been updated to include the size of the comet and to address its name.

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