Poll

5 votes (38.46%)
3 votes (23.07%)
2 votes (15.38%)
5 votes (38.46%)
2 votes (15.38%)
2 votes (15.38%)
1 vote (7.69%)
3 votes (23.07%)

13 members have voted

gordonm888
gordonm888
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Thanks for this post from:
Zuga
January 8th, 2021 at 7:03:23 PM permalink
Apophis is an elongated asteroid 450 × 170 metres in size, In length, it is taller than the Empire State Building and bigger in width. Apophis has not visited Earth since 1908, but will make "close approaches" in April 2029. and in 2036, and 2068. Read below and vote in our poll.




Close approaches
The closest known approach of Apophis comes on April 13, 2029, when the asteroid comes to within a distance of around 31,000 kilometres from Earth's surface. The distance, a hair's breadth in astronomical terms, is five times the radius of the Earth, ten times closer than the Moon, and even closer than some man-made satellites. It will be the closest asteroid of its size in recorded history. On that date, it will become as bright as magnitude 3.1 (visible to the naked eye from rural as well as darker suburban areas, visible with binoculars from most locations). The close approach will be visible from Europe, Africa, and western Asia.

The April 13, 2029, approach distance to Earth's surface is projected to be closer than 31,200 kilometres (19,400 mi) with a 3-sigma uncertainty region of about ±700 km. I hope they did their math right!

The approach in late March 2036 will be no closer than 8.4 million km (5.2 million mi).

In the 2060s, Apophis is expected to again closely approach Earth in 2066. On the April 12, 2068, Apophis could be more than 220 million km (140 million mi) from Earth, making the asteroid further than the Sun. However, on April 12, 2068, the odds of impact with Earth are 1 in 150,000 in large part because the line of variation (LOV) in its calculated orbit extends over 840 million km (522 million mi).

1 in 150,000? Sounds like an interesting prop bet.
Last edited by: gordonm888 on Jan 8, 2021
So many better men, a few of them friends, are dead. And a thousand thousand slimy things live on, and so do I.
Greasyjohn
Greasyjohn
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January 8th, 2021 at 7:09:51 PM permalink
About 66 million years ago an astroid about 6 (some sources say 9.5) miles in diameter hit the earth. It was equal to 10 billion atomic explosion.

2-15-13 a 60 foot diameter meteorite traveling at 40,000 miles an hour Exploded in the atmosphere over Russia. (There are several YouTube videos on this.)

On 15 February 2013, Duende passed at a record distance of 27,700 km (17,200 mi) or 4.3 Earth radii from Earth's surface. It was 98 ft in diameter. (This is closer than Apophis, but Apophis is larger.)

March 2004 an asteroid 100 feet across, named 2004 FH came to within 26,000 miles of the earths surface.
Last edited by: Greasyjohn on Jan 8, 2021
odiousgambit
odiousgambit
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January 9th, 2021 at 2:48:48 AM permalink
Apparently it is not possible to nail down the future path of such objects even if you have very accurate current data on them. The sun has an effect on them called the Yarkovsky effect ... this is why they can't say for sure what will happen but have to give odds, though it is also possible they aren't satisfied with the data they have.

https://earthsky.org/astronomy-essentials/the-yarkovsky-effect-pushing-asteroids-around-with-sunlight
the next time Dame Fortune toys with your heart, your soul and your wallet, raise your glass and praise her thus: Thanks for nothing, you cold-hearted, evil, damnable, nefarious, low-life, malicious monster from Hell! She is, after all, stone deaf. ... Arnold Snyder
Doc
Doc
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January 9th, 2021 at 11:36:33 AM permalink
I voted, "Meh, I prefer lunar eclipses." My rationale for this vote is that I don't think it is realistic for me to expect to still be alive in April 2029. (My wife hates it when I point out such things.)
RogerKint
RogerKint
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January 9th, 2021 at 11:59:15 AM permalink
Quote: odiousgambit

Apparently it is not possible to nail down the future path of such objects even if you have very accurate current data on them. The sun has an effect on them called the Yarkovsky effect ... this is why they can't say for sure what will happen but have to give odds, though it is also possible they aren't satisfied with the data they have.

https://earthsky.org/astronomy-essentials/the-yarkovsky-effect-pushing-asteroids-around-with-sunlight



We should probably close down the economy for two weeks just in case.
100% risk of ruin
Greasyjohn
Greasyjohn
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January 9th, 2021 at 1:30:12 PM permalink
Lets not forget about the Tunguska event of 1908.

https://en.m.wikipedia.org/wiki/Tunguska_event
gordonm888
gordonm888
Joined: Feb 18, 2015
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January 9th, 2021 at 1:34:32 PM permalink
Quote: odiousgambit

Apparently it is not possible to nail down the future path of such objects even if you have very accurate current data on them. The sun has an effect on them called the Yarkovsky effect ... this is why they can't say for sure what will happen but have to give odds, though it is also possible they aren't satisfied with the data they have.

https://earthsky.org/astronomy-essentials/the-yarkovsky-effect-pushing-asteroids-around-with-sunlight



The Yarkovsky effect (radiation pressure of sunlight on a rotating asteroid) will only be significant on close approaches. So after the 2029 close approach they will have much more information with which to predict the asteroids approach distance in 2068.

China is planning an unmanned space shot in 2022 that will last 6 years and has a three part mission
- study Apophosis
- do a flyby on another smaller asteroid
- send an unmanned space probe to land on a third asteroid.

By the way, the second syllable of "Apophosis" is emphasized.
So many better men, a few of them friends, are dead. And a thousand thousand slimy things live on, and so do I.
gordonm888
gordonm888
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January 9th, 2021 at 1:50:13 PM permalink
Quote: Greasyjohn

Lets not forget about the Tunguska event of 1908.

https://en.m.wikipedia.org/wiki/Tunguska_event



Tunguska shock wave flattened trees over 830 sq. miles of a remote area of Russia. Attributed to a 100m meteor that disintegrated in the atmosphere about 3-6 miles above the surface. And, remember, Apophosis is estimated to be 470m by 170m, which is somewhat bigger. It is nowhere near an extinction event if it hits Earth, but it would probably be the most important event in human history to date.
So many better men, a few of them friends, are dead. And a thousand thousand slimy things live on, and so do I.
odiousgambit
odiousgambit
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January 10th, 2021 at 5:37:25 AM permalink
I have the idea that if you could ask an expert, that he would tell you that it is believed that a planet that has 'attracted' a smaller object tends to finally capture it over time. That could be by putting it in orbit, or perhaps collision is in fact more likely. That the object just keeps doing near misses indefinitely seems the least likely to me, no expert. Perhaps escape could happen by the slingshot effect too, as a possibility.

I've tried to confirm this by searching but can't find anything exactly.
the next time Dame Fortune toys with your heart, your soul and your wallet, raise your glass and praise her thus: Thanks for nothing, you cold-hearted, evil, damnable, nefarious, low-life, malicious monster from Hell! She is, after all, stone deaf. ... Arnold Snyder
billryan
billryan
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January 10th, 2021 at 1:16:13 PM permalink
If an object 100 meters by 100 meters entered the atmosphere, wouldn't most of it either burn up or break off so the objects hitting the ground would be only a fraction of the original?

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