The claim: A 62-mile-wide mega comet has entered the solar system
Expect some brilliant lights in the night sky this summer: The Delta Aquariid meteor shower, which started this month, will be visible until Aug. 23 producing bright fireballs typically visible after midnight and before dawn.
But some on social media claim a much more alarming celestial body is also headed our way.
"A 62-mile wide 'Mega-Comet' has just entered our solar system," reads a graphic shared in a July 22 Instagram post.
The tremendous mass of ice, rock and space dust – named Comet Bernardinelli-Bernstein after its discoverers Pedro Bernardinelli and Gary Bernstein of the University of Pennsylvania – is definitely real. But contrary to what the posts claim, it didn't just enter our solar system. And it's no threat to Earth.
USA TODAY has reached out to the posters for comment.
Comet first noticed several years ago
The colossal comet was first observed in 2014 during a study of archival data taken from the Dark Energy Survey, an international collaborative project that uses the Victor M. Blanco Telescope in Chile to map out the cosmos.
Because it orbited the sun at a greater distance than Neptune, the eighth and final planet in our solar system, the comet was originally classified as a trans-Neptunian Object, or TNO. Its classification changed this year when the iconic "tail," or coma – the stream of dust and gas released when a comet approaches the sun and heats up – was independently confirmed by the Las Cumbres Observatory network.
Technically, Comet Bernardinelli-Bernstein has always been in our solar system. Astronomers believe it originated from the Oort Cloud, a very distant region of space thought to be like a bubble enveloping our solar system made up of trillions of pieces of icy space debris. (The famous Halley's comet is thought to have come from this same cosmic neighborhood.)
The mega comet likely started its journey from this part of space about 3.7 trillion miles away from the sun.
By 2014, it was 2.7 billion miles away from the sun. At this point, it had entered our inner solar system, the region familiar to us that includes all the known planets.
Despite being so far away, its impressive dimensions are what caught the researchers' eyes. Measuring somewhere between 62 and 230 miles in diameter, Comet Bernardinelli-Bernstein is one of the biggest comets that has ever been found and is even 10 times larger than the asteroid that wiped out the dinosaurs, scientists say.
Comet will pass by Earth in 2031
The comet's gargantuan size is an estimate based on how much sunlight it reflects. While we could discover as it gets closer that it's actually even larger, this doesn't change what astronomers are sure of: The itinerant comet is unlikely to harm our planet.
"The size estimate has no effect at all on the trajectory that the comet will take... there is no possibility of this thing getting any closer to Earth than Saturn gets," Bernstein, the comet's co-discoverer and professor of physics and astronomy at the University of Pennsylvania, told USA TODAY in an email.
Scientists predict this trajectory will take the icy rock from its current point just past Neptune's orbit to near Saturn's orbit in 2031, which will be the closest it gets to Earth. It will then zip back out to the distant regions of our solar system. It will still be about a billion miles from Earth at that point.
It's important to note this isn't the first time the mega comet has passed by. Astronomers believe it last visited the inner solar system about 3 million years ago. It may make the voyage once again in another 5 million years, Bernstein said.
Our rating: Missing context
Based on our research, we rate the claim a 62-mile-wide mega comet has entered the solar system MISSING CONTEXT, because without additional information it could be misleading. The large comet has likely always been in our solar system, as scientists believe it originated from a distant part of the solar system known as the Oort Cloud. But it's no threat to Earth as some posts imply. At its closest point in 2031 it's still expected to be about a billion miles away from us.
Our fact-check sources:
USA TODAY, July 28, Keep your eyes to the sky: Twin meteor showers could produce fireballs this week
EarthSky, July 26, Delta Aquariid Meteor Shower 2021: All You Need to Know
Pedro Bernardinelli, June 20, Twitter thread
NASA, Nov. 8, 2018, New Insights on Comet Tails Are Blowing in the Solar Wind
USA TODAY, June 30, The largest comet ever discovered in modern times is zooming toward the sun
NASA, accessed July 29, Oort Cloud
Space.com, June 10, 2020, Halley's Comet and Others May Be Stolen Goods
Planetary Science Institute, accessed July 29, The Impact That Wiped Out the Dinosaurs
Space.com, July 1, Newly found mega comet may be the largest seen in recorded history
Gary Bernstein, July 29, Email interview with USA TODAY
Mashable, July 3, Why the mega comet is so fascinating – and not a threat to Earth
LiveScience, June 22, 2010, Human Ancestor 'Lucy' Walked Upright 3.2 Million Years Ago
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This article originally appeared on USA TODAY: Fact check: Mega comet won't pass Earth until 2031, no risk of impact