back to article Asteroid nearly gave Earth a new feature, two days after its discovery

On Saturday, the Catalina Sky Survey spotted a near-Earth asteroid of respectable heft – and today, it passed between us and the Moon. 2017 AG13 (the Minor Planet Center, MPC, entry is here) is about the size of a 10-storey building. Its velocity to Earth is 11 kilometres per second. It passed at 0.53 Lunar distance, or 203, …

Silver badge

Glad it missed

Unfortunately the diagram missed too. Wouldn't want to keep the same scale for any of the parts or show the path it is taking through the Earth Moon system. Despite the diagram, thanks for the great work and interesting find.

8
1
Mushroom

"2017 AG13 is fairly dim, which made it hard to spot until it was quite close"

Makes you wonder just how many we miss seeing altogether...?

17
0
Silver badge
Devil

You might not want to know. But at least the ones we miss will only be city wreckers and not plate busters. With those we'd have plenty of time to panic.

3
1
Silver badge
Mushroom

I guess it depends on which city you happened to be in at the time...

0
0
Silver badge

Then again, with a 2-day warning, you'd certainly be in wrong city if it managed to hit you...

0
0
Anonymous Coward

"2017 AG13 is fairly dim, which made it hard to spot until it was quite close"

Can we name it Katie Hopkins then? Please?

:)

11
1
Silver badge

"You might not want to know"

Mostly we see them _after_ they've gone past.

This has a lot more to do with them coming from the direction of the sun (lit from behind, so virtually impossible to see) and being lit up as they go past us than their dimness.

The moon is about as black as a piece of coal. Most of these rocks are somewhat duller than that.

0
0
Anonymous Coward

"The moon is about as black as a piece of coal"

source?

The surface of the moon is mostly described as light grey. The moon's albedo is ~0.1 whereas coal has a much lower value ~0.05.

If you are comparing snow, coal and the moon maybe you could say "the moon is about as black as coal" but without context I think your statement would be misleading for most people.

2
0
Anonymous Coward

All but the..

final one.

0
0
Silver badge

What if it had hit?

No possible impact site mentioned! Gee, it would have been interesting to find out where it might have hit. Which is safer: northern or southern hemisphere? Which city should be buying asteroid insurance?

0
4

Re: What if it had hit?

If I remember correctly, Buenos Aires was the first city the bugs took out. At least in the movie...

16
0

Re: What if it had hit?

Because if you're going to apply an adjustment to its trajectory, such that instead of missing the planet it hits, the possible impact point is... anywhere.

19
0
Silver badge

Re: What if it had hit?

To be fair you could probably specify a hemisphere...

I mean - one side of the earth was facing in the direction from which the asteroid came at the time it passed by - so I reckon that hemisphere was more 'at risk' than the other...

But yes - it's like asking which section of a tennis court the basket ball would land in if bowled from between the posts on a rugby pitch.

4
0
Anonymous Coward

Re: What if it had hit?

My family is from Buenos Aires and I say 'kill them all '

1
0
Silver badge

Re: What if it had hit?

At least in the movie...

If memory serves me right, the book while not openly stating it as the first implies it was the first hit.

0
0
Anonymous Coward

Re: What if it had hit?

It was a movie?

0
0

Re: What if it had hit?

Íf it'd had hit Earth's atmosphere it would most likely not have hit at all.

Note the comparison to the Chelyabinsk rock... At that size meteors don't burn up, but disintegrate/explode midair.

It's what you get with Youth.. Not patient enough to wait until they touch down and make a nice crater.. Noooo.... They have to do the whole "You don't need Nukes to make a Big Bang" right away.. **

** No... I deny any science here... This is the celestial Youf , Showing Off , playing chicken with the older bigger kids, and occasionally failing to miss.

2
0
Silver badge

Re: What if it had hit?

Could still seriously damage a small town.

Most likely to hit the sea of course.

0
0
Anonymous Coward

Re: What if it had hit?

It was a movie?

Yes, with a tenuous connection to the novel by Robert Heinlein. Read the novel instead.

0
0
Silver badge

Re: What if it had hit?

"At that size meteors don't burn up, but disintegrate/explode midair."

If the angle is shallow, yes.

Chebalinsk skimmed through the atmosphere for several hundred miles before breaking up.

On a steeper angle the airburst can bring a supersonic shockwave of superheated air to the ground.

if you have a lot of rocks, this can result in a very bad day (hot enough to melt surface rocks, resulting in a volcanic appearance without any nearby vulcanism - and there are a few places on the planet like this) - one researcher by the handle of craterhunter has been advocating this as a possible cause for the sudden extinction of north american megafauna and the younger dryas periods. Some of the supporting evidence is quite compelling, in particular "recently" melted surface rocks in southern North America with no supporting igneous activity.

2
0
Silver badge

Re: What if it had hit?

I looked at craterhunter's site, and I can say as a Google Earth monster that the 'crater' image he has on that page does appear to the untrained eye to be a blast site, but in fact is typical desert erosion that just happens to be arranged to look kinda radial in pattern.

Of course, I did have to find the site on Google Earth to be sure, and craterhunter neglected to provide a link or info. And it does look like his photos are a bit doctored to make the 'crater' stand out a lot. I've spent many years living and hiking on just such terrains. They're everywhere in the US Southwest, and that site shows a caprock layer around the edge of a bowl with erosion proceeding into the soft layers below the caprock. It's extremely typical of the desert here.

In short, cool as it sounds, I was not impressed with the "ancient airbursts killed the megafauna" theory based on that proposed location. Don't have much to say about other evidence, but I'd guess he's a bit of a kook. A fun one tho!

1
0
Silver badge
Mushroom

Re: What if it had hit?

"At that size meteors don't burn up, but disintegrate/explode midair."

Bolides!

2
0
Silver badge

Re: What if it had hit?

Younger Dryas period - isn't that when Atlantis was sunk?

1
0
Silver badge

Re: What if it had hit?

I thought it blew up...?

0
0
Silver badge
Coat

Re: What if it had hit?

Nah, Pam woke up and he was in the shower. It was all a dream.

0
0
Silver badge

So, how big was the asteroid in koala bears?

5
0
Silver badge

Yeah, and what was the speed on the 'sheep in a vacuum' scale?

0
0
Silver badge

Biggest fish fry in history

If it hit an ocean.

0
0
Gold badge

Re: Biggest fish fry in history

Pfffffft. Not even close.

8
0

This post has been deleted by its author

Silver badge
Mushroom

One of these days...

POW!!! Right in the kisser!"

6
0
Silver badge

Re: One of these days...

All right Ralph, if the Earth had a kisser, where would it be?

1
0
Silver badge

Re: One of these days...

Great, now you've just awoken a dozen Russian sleeper agents.

1
0
Silver badge
Coat

Re: One of these days...

"All right Ralph, if the Earth had a kisser, where would it be?"

France. At least that's what they claim.

2
0
Silver badge
Joke

Re: One of these days...

I don't know where the intake aperture would be, but I could make some educated guesses on the output vent!!

0
0

We still have Bruce Willis and team on standby, right?

6
0
Silver badge

No, Bruce can't help us now. Getting kinda long in the tooth. We need new heroes, men and women (and others) who will place their fragile bodies on the line for their planet. 'Git 'er done' types (like Bruce) who don't flinch when flipping the Nuke Gun lever to 'Auto.'

Um, is Chuck Norris still available...?

0
0
Silver badge
Coat

The asteroid belt wasn't created by God, it was created when Chuck Norris got mad and roundhouse kicked a planet.

5
0
Silver badge

Dang!

"Um, is Chuck Norris still available...?"

I had to check: Chuck is 76 while Bruce is still only a nipper at 61.

2
0
Silver badge
Headmaster

Re: Dang!

The question is which would take longer to get ready for action - either of those two or the space shuttle to take them up there?

0
0
Silver badge

I'd rather stick with Robert Duval and Mary McCormack

At least they had the right attitude: " Well, look on the bright side. We'll all have high schools named after us. "

0
0
Silver badge

Re: Dang!

Dolph Lundgren is available - and he actually has a chemistry degree under his belt too (studied at MIT).

1
0
Silver badge

Re: Dang!

These days he looks like he face-washes in his chemistry experiments.

1
0
Anonymous Coward

Fairy Dim and hard to spot?

A bit like most politicians debating the NHS crisis in Westminster.

16
1
Silver badge
Boffin

So close?

I'd best take my hat off, then.

btw - doesn't 'velocity' include a direction, not just a speed? And surely the quoted 11km/s isn't a constant differential? Just askin'...

3
0

Re: So close?

In science velocity is a vector and thus including a direction. However according to the dictionary it can simply mean speed. So I think it is one of these instances where a field of study has taken two words that mean the same and added a distinction that wasn't there, before they go out and pester people that actually use it correctly. (I don't actually know the historical development of this word though)

1
1

Re: So close?

I think vector is the one with the directional component. Though my memory is a little fuzzy these days

0
0
Silver badge
Boffin

Re: So close?

Yep, in physics velocity is a vector and so always includes a direction, as well as a speed.

However, in general English, velocity and speed mean the same thing.

1
1
Silver badge

Re: So close?

Interesting. The distinction felt artificial to me, then I just realized neither of the other two languages I speak (one of latin origin, one not) has different words to designate speed vs. velocity. Sure, there are a bunch of more or less synonyms, but as far as physical properties are being described, both have only one word for both the scalar and the vector...

1
0
Silver badge

Re: So close? Re:Vector

If I remember my A-Level and university maths, what a vector represents is dependent on the number of dimensions you're working in.

If you are working in one dimension, a vector and a scalar are the same thing. In two dimensions (the standard environment when you are learning vectors IIRC), a vector is normally described as a one by two array in a cartesian co-ordinate system, or a scalar and an angle in a polar co-ordinate system.

In three dimensions, a vector will be a one by three three array in cartesian, or a scalar and two angles in polar co-ordinate system.

I'm sure that some theoretical physicist or mathematician will point out that they work in more than three dimensions!

So the upshot of this is that if you are working in one dimension, taking the path of the asteroid as a dimensional frame of reference, the velocity, even if treating it as a vector can be considered the same as it's speed, and this is what most lay people will count as a velocity.

Of course, celestial mechanics is never that simple, and is normally in at least 4 dimensions.

0
1

Page:

POST COMMENT House rules

Not a member of The Register? Create a new account here.

  • Enter your comment

  • Add an icon

Anonymous cowards cannot choose their icon

Forums

Biting the hand that feeds IT © 1998–2017