Jump to content
Moontanman

Could the Earth have two moons?

Recommended Posts

If a planetary body about the size and mass of Ceres were to be captured by the Earth could it take up a stable orbit around the Earth? How difficult would the interactions be for the Earth Moon system to capture such a body? Also would such a capture take several years of interactions between the Earth, the Moon and the new body or would it be more of an immediate thing? 

Share this post


Link to post
Share on other sites
On 1/2/2019 at 5:35 AM, Moontanman said:

If a planetary body about the size and mass of Ceres were to be captured by the Earth could it take up a stable orbit around the Earth? How difficult would the interactions be for the Earth Moon system to capture such a body? Also would such a capture take several years of interactions between the Earth, the Moon and the new body or would it be more of an immediate thing? 

Earth does have a second Moon of sorts...It's called " Cruithne " 

https://theconversation.com/earths-other-moon-and-its-crazy-orbit-could-reveal-mysteries-of-the-solar-system-38010

Edited by beecee

Share this post


Link to post
Share on other sites
On 1/1/2019 at 6:35 PM, Moontanman said:

If a planetary body about the size and mass of Ceres were to be captured by the Earth could it take up a stable orbit around the Earth? How difficult would the interactions be for the Earth Moon system to capture such a body? Also would such a capture take several years of interactions between the Earth, the Moon and the new body or would it be more of an immediate thing? 

Fun thought experiment. I think a single interaction would work...

Assume the body has little more K.E. than consistent with escape velocity from earth.

Heading earthwardish, it passes ahead of the moon a little beyond Roche's limit, giving the moon some of its K.E. w.r.t. earth, enough that it is now in earth orbit.

Assuming the moon doesn't now have escape velocity, it will have an elliptical orbit with a perigee near its old orbital distance.

The body will similarly have an apogee near the moon's old orbital distance.

A few near misses would cause increasingly interesting orbits. It's possible that they would acquire non intersecting orbits. Then just wait a few million years for tidal forces etc to circularise their orbits. Tides on earth would be very interesting, but maybe not in a good way.

Unless one of these objects (re)acquires escape velocity or their orbits become non intersecting, I'd expect them to collide within a few years/decades and possibly coalesce eventually into one moon.

The meteor shower on earth would be terminally spectacular.

Share this post


Link to post
Share on other sites

With regards to tides on earth from a Ceres capture, as Ceres is only about 1% the mass of the moon, unless the orbital distance was significantly closer then the moon currently gets, wouldn’t the effects be essentially unnoticeable to the general public?

Share this post


Link to post
Share on other sites
44 minutes ago, Nod2003 said:

With regards to tides on earth from a Ceres capture, as Ceres is only about 1% the mass of the moon, unless the orbital distance was significantly closer then the moon currently gets, wouldn’t the effects be essentially unnoticeable to the general public?

To the ignorant subset of the general public, yes.

I'd assumed Ceres' mass was not much smaller than the moon.

Share this post


Link to post
Share on other sites

Well a 1% difference in a 5’ tide would be +/- 0.6”, which would be measurable certainly, but not visibly obvious.

Share this post


Link to post
Share on other sites

I was hoping for a stable orbit inside Earth's moon, any chance of that? Maybe a resonance orbit?  

Edited by Moontanman

Share this post


Link to post
Share on other sites
On 1/1/2019 at 6:35 PM, Moontanman said:

If a planetary body about the size and mass of Ceres were to be captured by the Earth could it take up a stable orbit around the Earth? How difficult would interactions be for the Earth Moon system to capture such a body? Also would such a capture take several years of interactions between the Earth, the Moon and the new body or would it be more of an immediate thing? 

3

time will tell

Share this post


Link to post
Share on other sites
40 minutes ago, Nod2003 said:

Well a 1% difference in a 5’ tide would be +/- 0.6”, which would be measurable certainly, but not visibly obvious.

A 1% difference in a 5’ tide would be +/- 0.6”

or

a 1% difference in a 50’ tide would be +/- 6”

 

If by 'unnoticeable,' you mean not measured, then many people have never noticed any tide. Only an ignorant subset of the general public are unaware tides exist or would be completely unaware of Ceres' tidal effects.

24 minutes ago, Moontanman said:

I was hoping for a stable orbit inside Earth's moon, any chance of that? Maybe a resonance orbit?  

Eventually tidal forces over millions of years might stabilise the orbit inside the lunar orbit. I can't think of anything faster.

Speculation: I suspect that as the moon/earth mass ratio is the highest of any satellite/planet in the solar system, the likeliest, perhaps inevitable, outcome is that Ceres would collide with earth or moon within a few centuries. (Or orbital mechanics would become an applied science.)

Edited by Carrock

Share this post


Link to post
Share on other sites
1 minute ago, Nod2003 said:

5’=60”

60”*.01= 0.6”

Oops... You responded to a couple of typos before  I corrected them.

Share this post


Link to post
Share on other sites

As I study and research done on many websites and places, I haven't found any article related to the "Could the Earth have two moons?". The details about moons and other satellites has been listed on the following links. These are very beneficial so if you really want to clear your doubt then must go through the following links.

https://earthsky.org/space/does-earth-have-a-second-moon

https://www.universetoday.com/92148/what-if-the-earth-had-two-moons/

https://blog.nationalgeographic.org/2009/01/16/could-earth-have-two-moons/    

Share this post


Link to post
Share on other sites
On 1/7/2019 at 12:44 AM, beecee said:

https://www.businessinsider.com/cruithne-is-not-earths-second-moon-2015-3

 

Not that Business Insider is a scientific authority, but I want to see how you respond.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.