Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A dwarf planet coming within 11 AU of the sun over the next 10 years

groups.io

Post reply on HN
Print view View original

41–50 of 330 posts

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#41

Post by MereInterest »

ptcrash wrote: post #15

Apologies if this is an obvious question but I'm not familiar with astronomy. Will this dwarf planet just pass through our solar system or is there a chance it will start to orbit our sun?

For the most part, conservation of energy dictates that bodies in orbit will stay in orbit, and bodies transiting the system will exit it. Think of it like a ball rolling down a hill, then back up a hill of equal height. By rolling downhill, it gains enough velocity to make it back up the hill.

There are exceptions, of course. An asteroid passing through an atmosphere may be slowed down by friction (aerobraking), and be captured in orbit. Passing near another orbiting body, the interloper can be sped up or slowed down (gravity assist). But both of those require getting pretty close to a planet, and space is really big (citation needed), so it's unlikely that it would be captured.

Edit: Looks like I had the same misinterpretation, that it was a rogue planet rather than an Oort/Kuiper belt object.

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#42

Post by jstanley »

jbay808 wrote: post #36
bewaretheirs wrote: post #30

Earlier quoted context omitted.

Just launch a deep-space telescope; it would be easier. Soft-landing the telescope on an airless body would be harder (in delta-V terms) than just launching it into an equivalent solar orbit. And the body would block about half your view of the sky at any one time.

Could you get a nice gravity boost away from the sun by just following it for as long as possible?

I think the point is that in order to follow it, you need to (at some point in time) be at the same place and with the same velocity. Then you'll follow it.

But the energy required to do that is almost the same as what it would be if the dwarf planet wasn't there. You could get onto exactly the same orbit for roughly the same amount of energy, and if you relax the requirement that there be a dwarf planet nearby, you can choose superior orbits.

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#43

Post by [deleted] »

Sharlin wrote: post #31
ceejayoz wrote: post #2

> could possibly reach magnitude 13 in early 2031 Don't get too excited about looking at this one; that's a bit brighter than Pluto, so you'd need a pretty decent telescope to spot it. https://en.wikipedia.org/wiki/Magnitude_(astronomy)#Examples

I believe this is absolute magnitude, and specifically, absolute magnitude as defined for comets [1]. At Saturn's distance, definitely not a naked-eye object in any case. [1] https://en.wikipedia.org/wiki/Absolute_magnitude#Cometary_ma...

[deleted]

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#44

Post by floatrock »

anfilt wrote: post #28
Meerax wrote: post #23

Is this something we could plan and manage to launch an orbiter/lander to in time? Has anyone thought about the possibility of slapping something like a telescope on that and letting it beam back data and images from veryyyyy far out eventually?

Like till it gets closer we dont even know if it would be suitable to put something like that on it. Although it does seem like interesting idea. However, we have sent probes much further than this object (aka the voyager missions). So it would mainly be useful for studying this object. So a telescope would be less than ideal since we could always in theory deploy a telescope much deeper into space if we wanted.

Interestingly, the voyager missions were also timed-events -- they were launched when they were because JPL realized it was a 1-in-175-year alignment of the outer planets that made it feasible to launch just a few crafts to visit the outer planets all in one go: https://en.wikipedia.org/wiki/Grand_Tour_program

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#45

Post by lamontcg »

jbay808 wrote: post #36
bewaretheirs wrote: post #30

Earlier quoted context omitted.

Just launch a deep-space telescope; it would be easier. Soft-landing the telescope on an airless body would be harder (in delta-V terms) than just launching it into an equivalent solar orbit. And the body would block about half your view of the sky at any one time.

Could you get a nice gravity boost away from the sun by just following it for as long as possible?

No, that's not how gravity boosts work. If you match speeds with an object you actually get zero boost.

The point of a gravity boost is to come in pretty hot (relative to the body you're boosting off of) and then go out pretty hot in a different direction. So you take your relative velocity vector at the point of the encounter and twist it around. By doing that you change your orbital energy around your central body (the sun) by a lot, and the other object will lose a similar amount to keep the bookkeeping equal.

If you have zero relative velocity compared to the thing you want a gravity assist off of you can't get an assist. It isn't like drafting a semi.

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#46

Post by 0-_-0 »

jbay808 wrote: post #36
bewaretheirs wrote: post #30

Earlier quoted context omitted.

Just launch a deep-space telescope; it would be easier. Soft-landing the telescope on an airless body would be harder (in delta-V terms) than just launching it into an equivalent solar orbit. And the body would block about half your view of the sky at any one time.

Could you get a nice gravity boost away from the sun by just following it for as long as possible?

I think it should provide a much stronger slingshot velocity boost than any other planet, however getting to 11AU first is not easy.

https://en.wikipedia.org/wiki/Gravity_assist

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#47

Post by isoprophlex »

tonmoy wrote: post #38
jessriedel wrote: post #27

Earlier quoted context omitted.

If you launch your telescope on a spacecraft and get it to match speed with the dwarf planet (which is necessary for a soft landing), there's not much point in actually attaching it to the dwarf planet. That just blocks the view of half the sky. Also, there will be nothing to see out there other than the dwarf planet itself.

Is that really true? If we manage to get a spacecraft get captured by the dwarf planet's gravity and orbit it, would that not be a lot less delta-V compared to if we made the spacecraft achieve the dwarf planet's orbit around the sun just by itself?

It's a dwarf planet of ~ 200 km diameter. The thing has a miniscule gravity well, it won't matter much compared to launching from earth and matching orbits with it, i think...

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#48

Post by seaman1921 »

vmception wrote: post #37
jessriedel wrote: post #27

Earlier quoted context omitted.

If you launch your telescope on a spacecraft and get it to match speed with the dwarf planet (which is necessary for a soft landing), there's not much point in actually attaching it to the dwarf planet. That just blocks the view of half the sky. Also, there will be nothing to see out there other than the dwarf planet itself.

and frozen aliens

perhaps the sun's heat exposes them :)

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#49

Post by messe »

jessriedel wrote: post #29
messe wrote: post #14

Earlier quoted context omitted.

Getting into orbit would be rather difficult, as the probe would have have to match the planets velocity at perihelion. My instinct says it’s probably just on the edge of doable (although I’m not sure on which side), but I haven’t crunched the numbers. It would almost certainly need to be launched on a Delta-IV or Falcon Heavy class vehicle. EDIT: s/perigee/perihelion. I could say periapse and be neutral, but perihel…

The speed of Rosetta's comet at perigee is, I think, significantly grater than the max speed of this dwarf planet. The dwarf planet has a much higher apogee, of course, but escape velocity, corresponding to infinite apogee, is finite and not that large, and Rosetta had to go much deeper into the Sun's gravity well. So, as a non-expert who hasn't done the numbers, I'd guess matching pace with the dwarf planet would be…

Somewhat unintuitively, thanks to the Oberth effect, it can be easier to reach escape velocity closer to an object, (Humorously portrayed in https://xkcd.com/1242).

Aside: if you are looking to learn more, I cannot recommend Kerbal Space Program enough.

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#50

Post by perihelions »

Sharlin wrote: post #31
ceejayoz wrote: post #2

> could possibly reach magnitude 13 in early 2031 Don't get too excited about looking at this one; that's a bit brighter than Pluto, so you'd need a pretty decent telescope to spot it. https://en.wikipedia.org/wiki/Magnitude_(astronomy)#Examples

I believe this is absolute magnitude, and specifically, absolute magnitude as defined for comets [1]. At Saturn's distance, definitely not a naked-eye object in any case. [1] https://en.wikipedia.org/wiki/Absolute_magnitude#Cometary_ma...

Not in this case: the +13 figure is a predicted *apparent* magnitude. The absolute magnitude 'H' as your link defines is the 'H' field in the OP link, which is +7.8. (Note that's 'H' from your link's section on asteroid magnitudes, not comets or stars -- they're all on different scales).

Here's the documentation for the fields in OP's data table:

"H Absolute visual magnitude. A table converting H to a diameter is available."

https://www.minorplanetcenter.net/iau/info/OrbElsExplanation...

Post reply on HN