# Asteroid zips past Earth

An asteroid spotted by Australian astronomers early in the week missed Earth by just 5.3 million kilometres. “2012 LZ1” was observed from Australia’s Siding Springs Observatory last Sunday, June 10th. At around 500m in diameter, the rock is considered hazardous. Happily, 2012 LZ1 slipped by well outside the orbit of the moon …

## COMMENTS

This topic is closed for new posts.

#### Can't wait...

To see how many 2012 Apocalypse nutters try to use this as a get out of gaol card... "the mayans would have been right, but their calculations were slightly out, etc etc"

Statistically I have better odds being hit by a meteor than winning the national lottery.

Maybe my numbers are about to come up!

#### Re. Statistically...

Wouldn't that depend on how many lottery tickets you buy?

#### Re: Re. Statistically...

Warning... bad maths to follow...

Statistically there's more chance of me winning the lottery than being struck by an asteroid. But it's a pretty likely event that *someone* will win the lottery.

But consider the odds from the asteroids perspective. There's similar odds of that asteroid being hit by the earth - unlikely, but if lots of asteroids buy lottery tickets to hit the earth, there's a fairly good chance that one of them will "win"... The Mayans were right, head for the bunkers/hills!

You'll be winning a tenner which, in lottery terms, is the equivalent of a 500m rock missing the prize by 5.3 million miles.

#### 4 days warning, and it's 500m across....

....good thing people are watching for them, but heck - that's not a lot of warning if it was spotted on a collision course. Hope they have some plans in place for that.

#### Re: 4 days warning, and it's 500m across....

I had the same thought.

So much for all the effort into monitoring near earth object and so much for all the noise and panic around various 10-30m objects.

#### Re: 4 days warning, and it's 500m across....

Right. Depensing on your location, at 500m it might still be worth it to get "elsewhere" one on this little ball. Could get a little crowded at the airports.

#### Re: 4 days warning, and it's 500m across....

Hmm, it's *possibly* enough time; I recall reading that a particular nuclear explosive device could vapourise a sphere of 100m diameter of rock so maybe 100 of these would be enough to reduce that kind of asteroid to bits small enough to burn up in the atmosphere.

So the question is, how many rockets can be launched in 4 days, and how many nukes can you stuff in each one?

#### Re: 4 days warning, and it's 500m across....

"...plans in place for that."

Nukes in space. It's the only way we can survive.

#### Re: 4 days warning, and it's 500m across....

NASA sent Bruce Willis and a crew of roughnecks into space to divert the course of the asteroid months ago.

#### Re: 4 days warning, and it's 500m across....

@S4qFBxkFFg, who asked :

...how many rockets can be launched in 4 days, and how many nukes can you stuff in each one?

I was about to suggest that you need to set aside several years of international diplomacy to renegotiate the terms of the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, because I believed that Nukes in Spa-a-a-a-ce were forbidden by it. However, Article IV declares that "States Parties to the Treaty undertake not to place in orbit around the earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner."

OK! Nukes on an intercept course for an inbound mountain are not in orbit, nor are they "stationed", so we can stand the lawyers down, and maybe even send them to observe at about the site(s) of impact for thousands of tons of irradiated gravel! Result!

#### "at about 20:00AM this morning"

That must be in Aardvark Standard Time.

#### Re: "at about 20:00AM this morning"

Australian time, understandable confusion for them, they are on the other side of the world.

#### Re: "at about 20:00AM this morning"

"Australian time, understandable confusion for them, they are on the other side of the world."

... and upside down

#### Re: "at about 20:00AM this morning"

"At the tone, the time will be 26 Railroad."

#### Re: "at about 20:00AM this morning"

' "Australian time, understandable confusion for them, they are on the other side of the world."

... and upside down'

Aha! So it was two minutes past midnight!

#### Re: "at about 20:00AM this morning"

Er, that's five minutes past midnight. They must be using a Nixie clock with Russian tubes.

#### When too much is too little

Missing Earth by "just 5.3 million kilometers." That's more than 10 times the distance the Moon is from Earth. Talk about just journalistic licence!

#### Re: When too much is too little

In astronomical terms that's still considered rather too damn close.

Others have made it rather closer, such as those that have skimmed off the atmosphere like a pebble over water (you can't really get much close without an impact), but most are suitably far away but close enough to be a concern. The concerns are generally due to the huge number of variables in calculating orbital trajectories of less massive objects and the vagaries of the measurements available.

Haha, stupid aliens, ya missed!

#### 5.3 million kilometers away

I guess that's too far away to hit it with a mining laser and scoop up free metals?

#### Blowing up

We would never try to blow one up, just nudge it off course by knocking into it. Think about it, we would then have hundreds of still dangerous bits of rock.

#### /me

ducks. Phew! That was a close one...

#### How big a hole would it have made if it had hit the Earth?

I'll go look it up.

Ever notice that most of these things arrived in-between Tuesday and Friday? I recommend lunch out on Tuesdays, as well as Fridays. One never knows...

#### Re: How big a hole would it have made if it had hit the Earth?

Wow. It'd take out a medium size US state. Or make a tsunami when it hit the ocean (75% odds),

It'll certainly make the evening news...

#### Re: How big a hole would it have made if it had hit the Earth?

With a land strike the resulting atmospheric debris would probably be a bigger concern globally. Whoever was standing on the X might disagree.

Think of it as nature's way of putting soot in the upper atmosphere to reflect the sun's radiation and cool this rock off.

#### Re: How big a hole would it have made if it had hit the Earth?

Calculator here:-

http://impact.ese.ic.ac.uk/ImpactEffects/

#### Re: How big a hole would it have made if it had hit the Earth?

A few random figures later:-

our Inputs:

Distance from Impact: 10.00 km ( = 6.21 miles )

Projectile diameter: 500.00 meters ( = 1640.00 feet )

Projectile Density: 8000 kg/m3

Impact Velocity: 72.00 km per second ( = 44.70 miles per second ) (Your chosen velocity is higher than the maximum for an object orbiting the sun)

Impact Angle: 10 degrees

Target Density: 2500 kg/m3

Target Type: Sedimentary Rock

Energy:

Energy before atmospheric entry: 1.36 x 1021 Joules = 3.24 x 105 MegaTons TNT

The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 1.9 x 106years

Major Global Changes:

The Earth is not strongly disturbed by the impact and loses negligible mass.

The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree).

The impact does not shift the Earth's orbit noticeably.

So this = BIG HOLE....

#### Re: How big a hole would it have made if it had hit the Earth?

Crater shape is normal in spite of atmospheric crushing; fragments are not significantly dispersed.

Transient Crater Diameter: 9.78 km ( = 6.07 miles )

Transient Crater Depth: 3.46 km ( = 2.15 miles )

Final Crater Diameter: 13.2 km ( = 8.22 miles )

Final Crater Depth: 644 meters ( = 2110 feet )

The crater formed is a complex crater.

The volume of the target melted or vaporized is 1.81 km3 = 0.435 miles3

Roughly half the melt remains in the crater, where its average thickness is 24.1 meters ( = 79.2 feet ).

#### Bah!

5.3 million kilometres. Would that be 5.3 trilometres?

#### Big Hole

My very sketchy research gives me the idea that a 500 m PHO such as this, if it were to strike earth, may yield an energy release equivalent to 3 Gigatons, or 60 Tsar Bombas. Or a "9" on the Torino Scale. Not a civilization-ender, but certainly a city-killer.

#### Hardware Problem?

I saw the video attached to the article. Are you sure all this fuss is not just from a stuck pixel on the monitor?

#### We had a close call in 1974

There were videos and still shots on Astronomy magazine of an object that went over USA in daylight and was apparently only about 20 miles up.

The glow of the object and the trail were very bright even though it was in broad daylight.

Estimates of the mass varied but it was probably between 500,000 and 1,000,000 Tons (or Tonnes).

The bang would have been very impressive the path had been 20miles (or 21 miles) closer to Earth.

This topic is closed for new posts.