Recent Near Misses

[Recusant]

On Thursday, February 2, an asteroid named 2017 BS32 came past the Earth at a distance of 101,214 miles (162,888 km). In astronomical terms, that's rather close. It's going to be back, but since it's estimated to be about 39 feet in diameter, even if it did hit it probably wouldn't cause much damage.

According to the article linked above, 2017 BS32 is the third asteroid in just the past four weeks to fly by within the orbit of the Moon. I did a search, and I also found 2017 AG13 (9 January), and 2017 BH30 (30 January). However, that last article mentions a near miss by 2017 BX (25 January), so it seems like there have been four.

It's been a busy neighborhood recently! 

[No one]

A collision is a near miss

[OldGit]

since it's estimated to be about 39 feet in diameter, even if it did hit it probably wouldn't cause much damage.

Well, I don't want it falling in my garden.

[Dave]

A collision is a near miss

If it hits smack in the middle it is a total miss of a miss.

[xSilverPhinx]

since it's estimated to be about 39 feet in diameter, even if it did hit it probably wouldn't cause much damage.

Well, I don't want it falling in my garden.

Are you sure? It would be worth a fortune.

[Ecurb Noselrub]

On the issue of how big the asteroid would have to be to even make it to earth, I found this:

"Consider a specific example. The Leonids arrive at the top of the atmosphere at 7272 km/s with a maximal mass of around 0.50.5 g. According to the article these particles are 0.010.01 m across. They reach the ground. If such a particle strikes the 3030 km high atmosphere at 4545 degrees it must travel around 4×1044×104 m before it hits the ground, mostly burning up. If it started at rest at the top of the atmosphere it would only accelerate to about 11 km/s. As you can see it very much depends on azimuth, latitude, meteor composition, and speed."

So, it depends. Let's hope for those that hit at 45 degrees.

[Dave]

Hmm, surely the angle is also critucal? You missed that off the list but mentioned 45 degrees at the end.

Between a xkimming tangential miss and a 90 degree hit is a whole lot of variables!

If it had to be a hit I would go for something going fast anf through the maximum amount of atmoshpere - assuming that journey would burn off the most mass and do the most atmospheric braking?

The 2013 Chelyabinsk meteor was a NEO that was approx 20m and maybe weighed 12 kilotonnes.

On account of its high velocity and shallow angle of atmospheric entry, the object exploded in an air burst over Chelyabinsk Oblast, at a height of around 29.7 km (18.5 mi; 97,000 ft).

So only small bits were found.

At 45 degrees it might have dug a very large hole!

https://en.m.wikipedia.org/wiki/Chelyabinsk_meteor#

[Ecurb Noselrub]

Hmm, surely the angle is also critucal? You missed that off the list but mentioned 45 degrees at the end.

Between a xkimming tangential miss and a 90 degree hit is a whole lot of variables!

If it had to be a hit I would go for something going fast anf through the maximum amount of atmoshpere - assuming that journey would burn off the most mass and do the most atmospheric braking?

The 2013 Chelyabinsk meteor was a NEO that was approx 20m and maybe weighed 12 kilotonnes.

On account of its high velocity and shallow angle of atmospheric entry, the object exploded in an air burst over Chelyabinsk Oblast, at a height of around 29.7 km (18.5 mi; 97,000 ft).

So only small bits were found.

At 45 degrees it might have dug a very large hole!

https://en.m.wikipedia.org/wiki/Chelyabinsk_meteor#

You know, I assumed that the "4545" degrees meant 45 degrees as an angle and just wrote 45 too many times.  Maybe he meant temperature.  Yes, the angle is important. At straight on it goes thru less atmosphere. 

[Recusant]

Is this an offline resource, Ecurb Noselrub? It sounds like an interesting article.

[Ecurb Noselrub]

Is this an offline resource, Ecurb Noselrub? It sounds like an interesting article.

It was just a physics blog.      http://physics.stackexchange.com/questions/47754/minimum-size-of-an-asteroid-to-actually-impact-earth

I should have cited it to begin with.

[Recusant]

Ah, OK. Thanks. 

[OldGit]

A small object landed close to me yesterday,  but maybe a pigeon was responsible.

[Icarus]

^    OG is ever the shrewd comedian......

[Recusant]

In a few days, this one will qualify for the thread. 

"A large asteroid is due to pass on April 29" | EarthSky

A big – very big – asteroid will pass relatively close to Earth on April 29, 2020. Asteroid (52768) 1998 OR2 will pass at a safe distance, at some 4 million miles (6 million km), or about 16 times the Earth-moon distance. It'll be the biggest asteroid to fly by Earth this year (that we know about so far); according to current estimates, it's probably a bit over a mile wide (2 km) and maybe twice that long. Closest approach will be April 29 around 5:56 a.m. Eastern Daylight Time (09:56 UTC; translate UTC to your time). Professional observatories have been pointing their telescopes at the huge space rock already. Amateur astronomers with smaller telescopes will also have an opportunity to see it as a slow-moving "star."

[Continues (including some GIF images of the asteroid)]

[billy rubin]

i find these things fascinating.

mostly because, geologically, they are not particularly rare.

and also because of hell creek, which would have changed my life had i known about at a different time.

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