Earth might have a tiny new moon | Hacker News Reader

Earth might have a tiny new moon

newscientist.com

100 pointsprostoalex41 comments

One of the facinating things about this is that simulations show that it "may have been captured by Earth around 2016–2017" [1].

In 2017 we had a visitor from outer space called ʻOumuamua :)

This new object is also about 2-3.5 meters according to wikipedia so I want someone to send a ship to capture this Van Neumann probe [2]!

(Yes I know it's not likely but it is cool to think about)

[1] https://en.wikipedia.org/wiki/2020_CD3

[2] https://en.wikipedia.org/wiki/Self-replicating_spacecraft

It's technically correct, but let's not cheapen the word moon for this rock. "Natural satellite" will do.

So, not Luna, but a diminutive Lunita? :)

Luniculum

Luna is a feminine noun in latin. So, lunicula.

Lunino

So now any space station can claim to be "moon-sized fortress"

Is there a petition to rename the ISS "The Death Star" yet?

That's no moon!

If it were a fair bit bigger it could be attached to the front of the ISS - you never know when things like that might come in handy...

Seveneves reference?

Yes - couldn't resist. :-)

A tiny asteroid captures the attention of astronomers that may have been around for a year, but will be gone in the spring.

Why are space agencies not scrambling to capture this one? It's a 5 ton virgin asteroid, the scientific value must be high.

Also, practicing emergency missions would prepare us for investigation of unusual objects like Oumuamua.

Paging Elon Musk...

We should call it Minmus.

This also happened in 2006. The 'moon' 2006 RH120 stayed with us for about 11 months.

Assuming that this isn't space Tesla, I'm curious how much damage it could bring to Earth if it hit it

Likely very little to none. Something that size mostly burns up in the atmosphere. Maybe a schoolboy would be slightly singed by a pebble while walking home.

https://www.space.com/6833-boy-hit-meteorite.html

Famous previous case:

https://en.wikipedia.org/wiki/Sylacauga_(meteorite)

Elon said "Not mine":

https://twitter.com/elonmusk/status/1232748533486276608

Zero damage. It weighs about 5T and has a diameter of a couple of meters - smaller than a lot of artificial satellites that have reentered.

Not really but kind of. In the same way we have hundreds of thousands of small satellite bodies.

I thought to be classified as a moon you needed a distinctly observable gravity field?

Technically the earth hasn't cleared it's orbit because of the moon.

So the earth is not a planet.

If we're going down to that level of pedentry (and why not?), the Earth is not a planet in that sense, it's part of a double-planet system.

That was Alan Stern's take if I recall correctly.

The Moon is ~2% the volume of the Earth, you are stretching the definition of similar pretty hard.

Also when you take into account that the moon is formed from the outer layers of the earth it lacks a lot of the heavy elements like iron that the Earth has in it's core making the mass about 1.2% of the mass of the Earth [1].

It's much smaller compared to the earth than you would think just by looking at it but it is still a very large moon for a planet the size of the Earth.

"Of all the moons of the eight planets, Earth's moon is by far the largest relative to its planet, with a diameter of 3476 km and hence a ratio to Earth's diameter of 0.2764. By comparison, the next largest moon relative to a major planet (Triton of Neptune) has a diameter ratio of just .0546." [2]

The moon is also larger than Pluto (in the same reference as above) :)

[1] https://www.universetoday.com/20489/moon-compared-to-earth/

[2] https://en.wikibooks.org/wiki/General_Astronomy/Planetary_Mo...

> The orbit isn’t stable, so eventually 2020 CD3 will be flung away from Earth.

But could we keep it if we wanted to? Is it possible to make any use out of it?

No much point - it's tiny. A Falcon 9 can put 3-4 times [1] that mass (~4,900kg [2]) into a stable low Earth orbit.

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

[2] https://en.wikipedia.org/wiki/2020_CD3

That’s no moon...

Curious question: what are the red-blue-green artifacts on the picture ? Is it due to the CCD sensor ?

I imagine this mini moon could be ejected from orbit if it gets sling shot by the moon in the right way.

If that's a moon then so's the ISS.

That's no moon. It's a space station.

They set you right up for that one ;)

Only natural satellites are considered moons.

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