We dodged a bullet today. It came within one half of the distance to the moon.
I got this notice in email from NASA about a surprise asteroid that gave us only one day of warning passing halfway between the Earth and the moon. It was the largest known asteroid to ever pass that close to Earth in observational history.
SURPRISE ASTEROID FLYBY: With little warning, on Sunday, April 15th, a “Tunguska-class” asteroid about the size of a football field flew through the Earth-Moon system. 2018 GE3 was discovered just the day before as it plunged inward from the asteroid belt. A quick-thinking amateur astronomer in Europe was able to record a video of the asteroid as it flew by.
With little warning, a relatively large asteroid flew through the Earth-Moon system on April 15th only 192,200 km (0.5 Lunar Distance) from our planet. 2018 GE3 was discovered by the Catalina Sky Survey approaching Earth on April 14th. Hours later, amateur astronomer Michael Jäger of Weißenkirchen Austria video-recorded the space rock rushing through the southern constellation Serpens:
“According to Wikipedia, 2018 GE3 is the largest known asteroid to pass that close to Earth in observational history,” says Jäger. “It was shining like a 13th magnitude star at the time of my observations.”
Based on the intensity of its reflected sunlight, 2018 GE3 must be 48 to 110 meters wide, according to NASA-JPL.
This puts it into the same class as the 60-meter Tunguska impactor that leveled a forest in Siberia in 1908. A more recent point of comparison is the Chelyabinsk meteor–a ~20-meter asteroid that exploded in the atmosphere over Russia on Feb. 15, 2013, shattering windows and toppling onlookers as a fireball brighter than the sun blossomed in the blue morning Ural sky. 2018 GE3 could be 5 to 6 times wider than that object.
If 2018 GE3 had hit Earth, it would have caused regional, not global, damage, and might have disintegrated in the atmosphere before reaching the ground. Nevertheless, it is a significant asteroid, illustrating how even large space rocks can still take us by surprise. 2018 GE3 was found less than a day before before its closest approach.
Based on an observational arc of only 1 day, 2018 GE3 appears to follow an elliptical orbit which stretches from the asteroid belt to deep inside the inner solar system. Every ~2.5 years the space rock crosses the orbits of Mercury, Venus, Earth, and Mars–although not necessarily making close approaches to the planets themselves.
NASA Jet Propulsion Laboratory has made an interactive orbit viewer available online here
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Around 1998 candidate Donald Trump in an interview about the arms-race mentioned Reagan’s shield, known as SDI. Maybe PUTUS now could be advised to put that back on the table when he meets Pres. Putin – after all he wants to stop the arms-race (unlike the swamp and Prime Minister May(day).
Good news in the long run: My grand children will mine it and live within a large rotating cylinder built from it.
If you watch the NASA animation from the link above, June 13, 2023, Mercury could be struck. Wouldn’t take much of a deviation in speed to make that happen.
Surely it’s regular orbit is now thoroughly disturbed? Passing that close to the Earth may have wound up its speed considerably. That slingshot thing.
True danger lurks.
It was close enough that they should have been able to get a good fix on it’s current trajectory. From that they should be able to get a pretty good idea what it’s next dozen or so orbits will look like.
Now that we know where it is, updated orbit tracks can be taken every decade or so as well.
MarkW
Maybe, maybe not.
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Look at Comet Shoemaker-Levy 9. Spotted only AFTER it broke apart after a close pass-by of Jupiter. They could not “back-calculate” even its second-to-last orbit close enough to actually determine how it tracked before breaking up: Only general estimates. And that with the relatively simple n-body problem of Jupiter, its closest 4 moons, and the single comet body. (Before breakup.) After break-up the smallest 26 smaller fragments quickly grew near-invisible, untrackable – and that with a well-known of their bigger brothers and sisters to track.
The collision bursts of gas and dust in Jupiter’s atmosphere of every fragment were each far larger than the diameter of earth. So even a single “invisible” comet breakup fragment would be truly catastrophic events. But not as profitable as carbon futures trading, so the enviro’s don’t care, won’t fund that NASA research.
Surely it’s regular orbit is now thoroughly disturbed? Passing that close to the Earth may have wound up its speed considerably. That slingshot thing.
True danger lurks.
If an asteroid big enough to destroy a civilization hasn’t hit earth in 5000 years of recorded history, why should we be worried about one hitting earth any time soon?
Stochastic variation.
Of course, we may not get hit for tens or hundreds of years.
Nobody knows. [Well, I certainly don’t!].
Auto
Such collisions are purely random events. Getting hit tomorrow is just as likely as getting hit some day 10K years from now.
The only thing we know for certain is that the longer the time period in question, the better the chances of getting hit become.
BTW, the Tunguska event was big enough to wipe out an entire city. We are fortunate that the place it did hit had very low population numbers.
If the Russian meteorite of 2 or three years ago had been a few feet bigger across, it would have done many times more damage. We were fortunate that it was on the small side.
Didn’t the meteor that created Meteorite crater in Arizona hit about 5K years ago? Wouldn’t have ended civilization as a whole, but it would have ended it anywhere within 100 miles or so of the impact spot.
Posted elsewhere:
The April 15, 2018 near fly-past was by a meteoroid about 80m in diameter, roughly the same size as the 1908 Tunguska air burst that levelled ~2000 square kilometres of Siberian forest – a circle about 50km in diameter.
The April 15 meteoroid would probably have broken up in the atmosphere, like the Tunguska impact. The airblast would be like a modern nuclear bomb. No big deal, unless you are close to the large airblast area – and then even a good umbrella would not help you. The airblast would easily take out a large city and its surrounding metropolitan area.
Here is a damage calculator for asteroid impacts (h/t to Jeff): http://www.purdue.edu/impactearth/
https://en.wikipedia.org/wiki/Tunguska_event
The Tunguska event was a large explosion that occurred near the Stony Tunguska River in Yeniseysk Governorate
(now Krasnoyarsk Krai), Russia, on the morning of 30 June 1908 (NS).[1][2] The explosion over the sparsely populated Eastern Siberian Taiga flattened 2,000 square kilometres (770 square miles) of forest, yet caused no known human casualties. The explosion is generally attributed to the air burst of a meteoroid. It is classified as an impact event, even though no impact crater has been found; the object is thought to have disintegrated at an altitude of 5 to 10 kilometres (3 to 6 miles) rather than to have hit the surface of the earth.[3]
The Tunguska event is the largest impact event on earth in recorded history. Studies have yielded different estimates of the meteoroid’s size, on the order of 60 to 190 metres (200 to 620 feet), depending on whether the body was a comet or a denser asteroid.[4]
https://www.gettyimages.ca/detail/news-photo/photograph-from-the-tunguska-event-was-a-large-explosion-news-photo/629465421?#photograph-from-the-tunguska-event-was-a-large-explosion-that-near-picture-id629465421
How long before CNN blames this event on global warming?
How long before – and the BBC, if it ever notices – blames to Russo-German gas price stitch-up on CAGW, too.
See – https://www.telegraph.co.uk/business/2018/04/12/leaked-eu-files-show-brussels-cover-up-collusion-putins-gazprom/
Auto.
MarkW April 16, 2018 at 7:12 am wrote
Greg, I’m sure your attempts to make Putin and Russia look better are appreciated. Somewhere.
I think Trump has cornered that market.
There is a claim out there that Russian internet trolling has increased 2000 percent since Trump raided Syria the other day. I guess we should keep our eyes open for disinformation from that group.