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

The first known object to enter our solar system from deep space

cbc.ca

Post reply on HN
Print view View original

21–30 of 114 posts

Re: The first known object to enter our solar system from deep space

#21

Post by Tossrock »

I recommend anyone interested read the paper which is available as a preprint from Nature (for the moment): goo.gl/cSsHoj (link shortened due to having an embedded access token).

Some tantalizing points from the paper:

- They constrained the aspect ratio in two dimensions to be 10:1:C, but the third dimension is unconstrained. Depending on which axis the object is rotating around, C could either be 1, or 20. Either of these would be an essentially unique object within the solar system. This is a really weird shape.

- If the object is rotating around its short axis, it must have internal tensile strength (ie, it's a solid object, not just a pile of dust/gravel accreted by gravity). Lower bound on the required tensile strength is 3 Pascal (very little).

- There is essentially no dust/ice on the object - less than 1 kg within 2.5". So it's not a comet, and would have to be asteroidal. This conflicts with our current understanding of what objects would be in interstellar space. Current models have almost all objects ejected from our system being icy comets. This object would be analogous to a Manx comet, ie a rocky asteroid in a highly elliptical long period orbit.

- The shape of the observed light curve deviates from the best-fit triaxial ellipsoid in a way that suggests large flat or concave sections. It would take unrealistically large albedo variations to produce the same deviation without flat/concave sections.

And of course, of all the planets in the solar system, it made its closest approach to Earth, an astronomical "near miss" at just 0.16 AU :)

Re: The first known object to enter our solar system from deep space

#23

Post by Santosh83 »

z3t4 wrote: post #17

How close to earth did it pass ? A possible extinction event just flew bye and there where nothing we could do about. Btw, that looks like a gravity assist/slingshot ...

We aren't able to do much about the ongoing anthropocene extinction event either.

Re: The first known object to enter our solar system from deep space

#25

Post by robin_reala »

Tossrock wrote: post #21

I recommend anyone interested read the paper which is available as a preprint from Nature (for the moment): goo.gl/cSsHoj (link shortened due to having an embedded access token). Some tantalizing points from the paper: - They constrained the aspect ratio in two dimensions to be 10:1:C, but the third dimension is unconstrained. Depending on which axis the object is rotating around, C could either be 1, or 20. Either o…

And of course, of all the planets in the solar system, it made its closest approach to Earth, an astronomical "near miss" at just 0.16 AU

That is presumably because there’re lots of these objects, but we can only detect the ones closest to us.

Re: The first known object to enter our solar system from deep space

#26

Post by tehwalrus »

Tossrock wrote: post #21

I recommend anyone interested read the paper which is available as a preprint from Nature (for the moment): goo.gl/cSsHoj (link shortened due to having an embedded access token). Some tantalizing points from the paper: - They constrained the aspect ratio in two dimensions to be 10:1:C, but the third dimension is unconstrained. Depending on which axis the object is rotating around, C could either be 1, or 20. Either o…

- strange aspect ratio

- tensile strength (it should be cartwheeling, there is a physics theorem which means everything tends to this configuration)

- large flat or concave sections.

- others are reporting it's mostly metallic.

I'll say it: did anyone consider an alien spaceship? The paper seems to deduce "asteroidal" by ruling out other things, rather than by a positive measurement of rock spectra, unless I've misread it.

Re: The first known object to enter our solar system from deep space

#28

Post by Tossrock »

robin_reala wrote: post #25
Tossrock wrote: post #21

I recommend anyone interested read the paper which is available as a preprint from Nature (for the moment): goo.gl/cSsHoj (link shortened due to having an embedded access token). Some tantalizing points from the paper: - They constrained the aspect ratio in two dimensions to be 10:1:C, but the third dimension is unconstrained. Depending on which axis the object is rotating around, C could either be 1, or 20. Either o…

And of course, of all the planets in the solar system, it made its closest approach to Earth, an astronomical "near miss" at just 0.16 AU That is presumably because there’re lots of these objects, but we can only detect the ones closest to us.

The authors estimate that there is ~1 such object within 1 AU of the sun at any given time. So, more common than we previously expected, but not exactly teeming. You're right that it was detected due to its nearness though - it was picked up in a routine near-Earth object survey by Pan-STARRS

Re: The first known object to enter our solar system from deep space

#29

Post by nichtich »

If there're a lot of these objects entering and leaving solar system every year, and suppose some day in the near future we can keep track of them all, can we use them for us to send out larger probes? We see a rock coming near us, and send out a probe to its path. And before the collision the probe create a buffer object at the rear end so that it wouldn't be totally destroyed. After that the probe can free ride for a while at a high speed and re-ignite when it decides to go a separate path.

Re: The first known object to enter our solar system from deep space

#30

Post by vortico »

What was its speed at closest sun approach? Because the speed of objects in our solar system are all very low compared to the speed of the nearest solar system compared to our sun, I imagine this could also be the fastest object ever to be obversed in our solar system.
Post reply on HN