Celestia Forums

In the past dozen years, seven asteroids are known to have passed closer to the Earth than the orbit of the moon, just barely missing us. I wonder how many weren't noticed?

The orbits of these seven Near-Earth Objects are now available for adding to Celestia at http://www.lns.cornell.edu/~seb/celestia/minor-planets.htlm#3.2.2

Did any of these objects pass close enough to have their orbits significantly altered by the encounter?

- Hank

O YES SOME WERE VERY VERY VERY CLOSE . Ond was found 4 days AFTER
it past between the Earth and Moon.

I wonder what a 1,500,000 MegaTon blast would look like Haroshima was 1.5 MT the bikini atol H -Bomb was 80 MegaTon

How much VERY VERY VERY CLOSE ???

Kendrix,

Look on the Web page. Currently, the units there are in AU, but I'll be adding more information as I have time. The closest one was at a distance of about 0.0007 AU = about 100,000 km.

Of course, the trajectories of *all* Near Earth Objects get modified by their close approaches to the Earth. For ease of reproducing the flybys themselves, I'm currently supplying elliptical elements valid near the times of their closest approaches.

I hope to add xyz trajectories as well as elliptical elements for opposite sides of the encounters so that people can see just how much the asteroids' orbits were modified.

Several of these NEOs will be coming back to visit us in the future, too. (If at first you don't succeed, try, try again...) I've included InfoURLs for them, since the returning NEOs have their own Web pages on NASA's NEO Web site.

john Van Vliet wrote: I wonder what a 1,500,000 MegaTon blast would look like Haroshima was 1.5 MT the bikini atol H -Bomb was 80 MegaTon

The bombs used on Japan were less than 15kilotons! Which makes a 100-megaton bomb all the more unimaginable.

Tim Crews

I've added another 4 NEOs to the file of SSC catalogs. There (at least) 4 asteroids that are known to be coming closer to the earth than the moon in the not too distant future. Of course, there will be many more in the meantime that they haven't discovered yet.

The ssc files of the previous 7 have been updated to have InfoURLs pointing to pages on the NeoDys Web site. Their pages seem to be more detailed than JPL's.

Additional comments as well as a link to the zip file can be found at http://www.lepp.cornell.edu/~seb/celestia/minor-planets.html#3.2.2

Want an idea of what something like that would look like. See the movie Deep Impact. The impact was quite well done and gives an very good idea of what would happen even if a small asteriod hit the oceans. We have to remember that a small asteriod hitting the land would be bad but one comming down in the middle of the Pacific or Atlantic Oceans would be tens times worse. The Earth is 70% covered in water so there is a 70% chance that an impact will hit there. The Tsunami that would form would be a thousand feet high when it came in in shore and would travel all the way to all the coastlines inundating every city there. Millions would die because they simply couldn't get out of the way fast enough. The Tsunami would be moving at over 700 miles per hour. If one hit in the Pacific within hours Loa Angeles, San Francisco, Portland, Seatle, Anchorage, most of Japan, Tiawan, Hong Kong, and countless other cities would be whiped off the face of the Earth. The wave would also move quite far inland in the lower regions. In California alone we would loose the entire central valley farm lands. the whole thing would be under salt water for months. This would bring the world economy to its knees.
Oh well enough doom and gloom.
Don.

For a fun ride, do the following:

1. Select one of the NEOs in the Solar System Browser.
2. Goto.
3. Crtl-left drag to get farther away from it so it doesn't take up your entire field of view. (For PC -- don't know the analog for Mac)
4. Select Earth and track. (Hit 'T')
5. Speed up time to 100000x, 1000000x, 10000000x or more. (Hit 'L' repeatedly)

In the right era (1990s, 2000s or so) you fly by Earth closely enough to make out the Earth-Moon system very clearly. During the flyby your field of view spins all around as you move in relation to Earth. Weeeeee!

For a fun ride, do the following:

1. Select one of the NEOs in the Solar System Browser.
2. Goto.
3. Crtl-left drag to get farther away from it so it doesn't take up your entire field of view. (For PC -- don't know the analog for Mac)
4. Select Earth and track. (Hit 'T')
5. Speed up time to 100000x, 1000000x, 10000000x or more. (Hit 'L' repeatedly)

In the right era (1990s, 2000s or so) you fly by Earth closely enough to make out the Earth-Moon system very clearly. During the flyby your field of view spins all around as you move in relation to Earth. Weeeeee!

john Van Vliet wrote:O YES SOME WERE VERY VERY VERY CLOSE . Ond was found 4 days AFTER
it past between the Earth and Moon.

I wonder what a 1,500,000 MegaTon blast would look like Haroshima was 1.5 MT the bikini atol H -Bomb was 80 MegaTon

Its Hiroshima, and it was a mere 14 kiloton, not megaton. And the biggest bomb ever tested was just 60 megaton, and that one was a Russian bomb, wich was detonated above Nova-Zembla (they where about to test a 100 megaton device, but canceld it because they feared it may so called shatter their own windows).

Even the eruptions of the volcanos Krakatau and Tambora pale in comparison with and impact of a small asteroid. Maybe it can be compared with a so-called Super-eruption, such as the Toba-super-eruption wich took place about 74.000 years ago and nearly wiped out the human-race. Research estimated that somewhere between 20.000 and 40.000 humans survived that disaster worldwide, so that should give you an idea how catastrophic the impact of a small astroid would be, a large one would kill us all.

One description of the effects of the Toba eruption can be found at http://www.bradshawfoundation.com/evolution/

HankR wrote:Did any of these objects pass close enough to have their orbits significantly altered by the encounter?

Selden wrote:I hope to add xyz trajectories as well as elliptical elements for opposite sides of the encounters so that people can see just how much the asteroids' orbits were modified.

I've made a quick xyz for 1994 XM1, the closest approach by an asteroid to earth in recent times. It comes VERY close, and it's orbit is significantly altered... Get the file from here: http://homepage.eircom.net/~jackcelestia/files/1994xm1xyz.zip

What about Hawaii, I heard that one of the valcainios is going to fall into the ocian, thears already a great big crack in the island.

What halvic would that caus?

star lion wrote:What about Hawaii, I heard that one of the valcainios is going to fall into the ocian, thears already a great big crack in the island.

What halvic would that caus?

Unless Hawai'i is going to do the same, you're probably thinking of La Palma (I've probably spelt that wrong), in the Atlantic. In which case, apparently you'll have to kiss the eastern seaboard of the US, and much of Europe goodbye.

I don't think there's enough duct tape in the world to hold THAT together .

Still, as with all these things, given our current technology and general lack of interest by our governments in anything that lasts on a longer timescale than one term of office, I think the best thing to do if an asteroid impact or mega-eruption or whatever happens is to either enjoy the show, or bend over and kiss your arse goodbye . Putting a paper bag over your head is optional, but it won't help . Either way, whether you'd survive or not is probably largely down to luck anyway.

Of course, if it ever gets to the point where we CAN track and stop any NEAs big enough to be a threat, then it becomes more a matter of skill than luck. Though currently, I thought I saw an article recently saying that we're on track to identify every NEA over 1 km in radius by 2010... but all that means is that we know where the ones that might cause a major mass extinction are. We still won't know where the smaller ones are, that could potentially wipe out a city if they landed on it. (had the object that blew up above Tunguska, Siberia in 1908 blown up above London or New York, could easily have destroyed the city and killed millions. We got lucky there).

Which is all the more argument for getting some eggs out of the one basket called the Earth and onto another planet, really.

Its either La Palma or Las Palmas, i am not sure either, but this is indeed another disaster waiting to happen. There is already a crack in the island and it is not a question of it will happen, but when. A part of the island will slide into sea and causing a tsunami that will wipe out much of the Eastern coast of the USA. I am not sure about damage to Europa and the rest of the Atlantic ocean, but low islands in the Carribian and countries like the Netherlands (i live about 3 meter below sealevel but my appartment is at the fourth floor), belgium, parts of Germany, England will surely be affected, as will all coastal towns along the Atlantic Ocean.

This giant landslide has happend before, just like the super-eruption wich took place at Toba 74.000 years ago. And it will happen again.

The asteroid that killed of the dinosaurs was just the final nail on their coffin, the earth saw a mass-eruption at that time that formed the Deccan-traps in India, that was the real killer. The impact was a mercy killing for an Eco-system already shot to pieces by Mother earth herself.