First interstellar visitor discovered

[jmorgan]

http://www.skyatnightmagazine.com/news/first-inter...

Seems Oumuamua was just a day tripper in comparison. Not even a full day, just nipped in for an ice cream then out again.

2015 BZ509 orbits the sun in the retrograde orbit in comparison, shares Jupiter orbit. The reckon it is been here since we started. We as in solar system.

[Eric Mc]

How have they worked out that it is something that formed outside the solar system?

[jmorgan]

Guessing as it is going the wrong way.

[Eric Mc]

jmorgan said:

Guessing as it is going the wrong way.

Some of the solar system's moons go around their planets the wrong way too. It's never been properly understood why this might be.

[AshVX220]

Do orbits go in the same direction based on the spin of the main body, or is there something else that causes it?

[Eric Mc]

AshVX220 said:

Do orbits go in the same direction based on the spin of the main body, or is there something else that causes it?

Not quite. It is generally thought that planets and moons etc form from an already spinning cloud of dust and debris. This cloud's spin would be in one direction. Therefore, the planets etc retain the original direction of spin that would have been the spin of the cloud. If something exists in the system that has a retrograde motion (i.e. spin in an opposite direction) the assumptions are -

it wasn't part of the original spinning cloud i.e. an interloper from outside.

it WAS part of the original spinning cloud but had its original direction of spin significantly altered due to a catastrophic event such as a collision with another body oer a gravitational peturbation from a near miss.

[jmorgan]

Typically the solar system formed from a mass that was spinning the same way. Venus goes around the sun the same way but it spins the other way to the rest of us. Triton orbits the wrong way but some theory that it is also a captured object.

I think.

Guessing that the few that Jupiter has etc. are captured, however I understand this is not a moon but an object going the wrong way.

Edit. They have been quick on wiki,
https://en.wikipedia.org/wiki/(514107)_2015_BZ509#...

Edited by jmorgan on Wednesday 23 May 14:38

[AshVX220]

Thanks Both.

[Eric Mc]

I remain to be convinced that it's retrograde orbit is due to it being from somewhere outside the solar system. There is a strong argument that there is a shell of material (called the Oort Cloud) which completely surrounds the solar system. It is thought that comets originate from that cloud and , for whatever reason, fall out of the cloud and in towards the sun. Some comets have retrograde orbits.

I wouldn't be surprised if this is an Oort Cloud object which has fallen into the inner solar system and been given a more circular (although retrograde) orbit following a gravitational interaction with some other solar system object such as Jupiter or Saturn.

[jmorgan]

I suppose the only way to be sure is go get a sample. However they did say they ran back in simulations and the orbit works, though I understand that Jupiter was a bit of a hooligan in its yoof and one theory is it took a wander through the solar system. Obviously not for the hell of it but part of the early formation.

Edit. The "they" are in here
https://academic.oup.com/mnrasl/article/477/1/L117...

Edited by jmorgan on Thursday 24th May 08:43

[Einion Yrth]

jmorgan said:

I suppose the only way to be sure is go get a sample.

Best of luck getting anything into a solar retrograde orbit and back again, the deltaV requirements must be off the charts.

[Eric Mc]

Einion Yrth said:

Best of luck getting anything into a solar retrograde orbit and back again, the deltaV requirements must be off the charts.

The orbit of Halley's comet is retrograde. In 1986 the European Space Agency sent a probe (Giotto) to rendezvous with the comet - so it can be done. However, getting a sample and returning it to earth would be monstrously difficult. Rendezvousing and remote sampling and returning the data by telemetry is definitely something that could be done - a bit like Rosetta.

Solar system objects with retrograde orbits are not unknown. They are not common - but they do exist.

[Eric Mc]

Report on BBC Radio 4's "Inside Science" at 13.10 into the programme.

https://www.bbc.co.uk/programmes/b0b39v74