Incoming ‘Moby Dick' asteroid goes missing near Earth | Hacker News Reader

Incoming ‘Moby Dick' asteroid goes missing near Earth

newscientist.com

43 pointsColinWright20 comments

Article says it was last seen 14 years ago, so it's obviously not some asteroid we've been monitoring too recently that just inexplicably disappeared like I, someone who doesn't know much about astronomy, assumed from the title. We apparently were just wrong in calculating its trajectory..

The "incoming" in the title suggests a trajectory aimed at grabbing eyeballs and clickthroughs. :-)

As does "goes missing near Earth" I don't think going missing 14 years ago equates to going missing near Earth.

3.4 million kilometers at closest approach doesn't even equate to "near Earth". But what better can you expect from the New Scientist?

Exactly, calculating trajectories (accurately) is very difficult. I did a summer project at JPL where we would take astrometric measurements of various minor planets (including Pluto) and then update the trajectories. Even a big, well studied object like Pluto could easily be an arcsecond or two away from where it was "supposed" to be. (For reference, at Pluto's distance, that would be ~30,000 km off.)

But it's also possible that it's right where it should be and is too faint to be detected. Asteroids are very hard to detect because they're faint and they move -- so you can't expose the image for a long time to detect a fainter image. All you would get would be a faint streak across the image.

Not if you moved the lens in time with the supposed trajectory.

Yes, tracking is one technique to get around this. It's generally difficult (though not impossible!) for a few reasons. The first is that most telescopes are set up to track the sky -- they can move pretty uniformly along with the rotation of the earth, but they're much jerkier when moving to other locations on the sky. In an alt-az telescope this doesn't matter, but most telescopes aren't built on alt-az mounts.

The other reason this is difficult to do is because it's hard to guide the telescope. The bright guide stars you're using to correct for the small motions the telescope is making due to wind, etc. are now moving in your field of view and can't be used to guide the telescope.

Finally, you have to know the trajectory pretty well to do this. You have to not only know how fast to move the telescope, but the right direction to move the telescope. This can be done for a well studied object where the uncertainty in the trajectory is pretty small. But if the object hasn't been observed for 14 years, you probably won't have very good knowledge of its trajectory.

Here's a nice press release (http://neo.jpl.nasa.gov/news/news182a.html) regarding the impact of a small NEO (2-3 meters in size) last month with Earth.

Being small, it was discovered only 21 hours before impact, and its sonic signature is believed to have been observed in the mid-Atlantic around Bermuda.

Larger asteroids with orbits that will come near Earth's are being discovered routinely by sky surveys (e.g., Catalina, http://www.lpl.arizona.edu/css/css_mission.html) as far away as Jupiter.

Are you joking? Yesterday it seems like a meteor impacted the province of Santa Fe in Argentina: http://zeenews.india.com/news/space/scientists-probe-meteor-...

Why nobody connected it with this "Moby Dick" ?

Because unless there's some proof, there's no reason to believe that the two events are related.

Case in point: last year's meteor event over Chelyabinsk, Russia took place shortly before a publicized close-pass of Earth by asteroid 367943 Duende. Many people quickly jumped to the conclusion that the two were related when, in fact, they were conclusively not.

It was not a conclusion just nobody pointed the provable connection.

Sorry you are wrong about the scientific method. The proof came later, the hypothesis first. If two improvable events came together it's worth the investigation beyond if the events are related at the end or not. When I said connection I meant two events happening at the same time.

For comparison, the asteroid from the extinction level event which killed the dinosaurs was about 5 kilometers in diameter.

And the object that exploded over Chelyabinsk last year was estimated at 20m in diameter.

So 270m, while a long way off "catastrophic", is well into "serious".

It could still be catastrophic. If it hit a large city, it could immediately wipe out millions of people. If it hit the ocean near the shore, it could create massive tsunamis. If it fragmented into tiny particles on impact or caused a huge firestorm, it could block out enough sunlight to cause a "nuclear winter" scenario:

"Similar climatic effects are believed to have followed large comet and asteroid impacts in the past, due to sulfate bearing rock being pulverized and lofted high into the air combined with the ignition of multiple forest firestorms, which is sometimes termed an impact winter..."[1]

[1] https://en.wikipedia.org/wiki/Nuclear_winter

Not to mention if it came down in a politically tense time and the ensuing confusion triggered us to deploy the instruments of our civilization's destruction, which we like to keep ready at hand.

I think I remember reading that one. Lucifer's Hammer, right?

> If it hit a large city, it could immediately wipe out millions of people.

I'd bet that an ocean impact would be worse, the resulting Tsunami could level dozens of cities.

Every good SF reader knows that an asteroid that suddenly disappears is actually an alien spaceship. :-)

This is really interesting because there seem to be two camps on this. A lot of stories are reporting the asteroid as missing, while others report pictures taken by the Dubai Astronomy Group. One of those camps has it very wrong. http://www.express.co.uk/news/science-technology/460471/Aste...

One of the ones that got away?

http://en.wikipedia.org/wiki/1490_Ch'ing-yang_event

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