Starship Asterisk*

FloridaMike wrote:Nit, your picks are most entertaining, thank you.

Billsey wrote:

Chris Peterson wrote:

Billsey wrote:Is that a comet just to the right of the solar mask?

Looks to me like a cosmic ray hit on the detector.

Well, i don't know what one of those would look like, so it is entirely possible. Looking back at the smear in question, it has what looks like a head at the left end with the smear trailing off behind it, and, while at first look it doesn't seem to align with the jets of the solar wind, that could be the result of being turned in the third dimension with the resulting foreshortening of the smear. It is most likely that someone else would already have reported a comet, though, if that is what I am seeing.

Chris Peterson wrote:

Billsey wrote:Is that a comet just to the right of the solar mask?

Looks to me like a cosmic ray hit on the detector.

Chris Peterson wrote:

Billsey wrote:Is that a comet just to the right of the solar mask?

Looks to me like a cosmic ray hit on the detector.

Billsey wrote:Is that a comet just to the right of the solar mask?

neufer wrote:

Chris Peterson wrote:
I expect, however, that there are theoretically possible scenarios for an Earth capture, if we include additional interactions with other gas giants.

That would be a challenge :!:

Neufer wrote:

Nitpicker wrote:

APOD Robot wrote:
Sun-orbiting SOHO spacecraft

That's a reasonable enough description for me. Sorry for doubting you, APOD Robot. <backflip emoticon>

It can only be attributable to human error. The 9000 series is the most reliable computer ever made. No 9000 computer has ever made a mistake or distorted information. They are all, by any practical definition of the words, foolproof and incapable of error.

Beyond wrote:
Nomad must have been series 8999.

Chris Peterson wrote:
I expect, however, that there are theoretically possible scenarios for an Earth capture, if we include additional interactions with other gas giants.

neufer wrote:The minimum relative velocity starts at ~17 km/s at a point where Jupiter's escape velocity (at ~4.2 AU) is just ~0.65 km/s. The Earth would have to hit Jupiter's atmosphere just right to lose all of this tremendous excess kinetic energy but without burning up entirely as a giant meteorite in the process. Unfortunately the first aerobraking event would be so severe that the Earth would shortly skip reentry into Jupiter permanently. (So the answer is no.)

Nitpicker wrote:

APOD Robot wrote:
Sun-orbiting SOHO spacecraft

That's a reasonable enough description for me. Sorry for doubting you, APOD Robot. <backflip emoticon>

APOD Robot wrote:Sun-orbiting SOHO spacecraft

Chris Peterson wrote:

Ann wrote:
But if the Sun disappeared, both the Earth and the Moon (and all the other planets in the no longer solar system) would just go off on a tangent, right?

Is there any chance that the Earth-Moon system would get captured by Jupiter and end up in orbit around Jupiter?

It seems very, very unlikely. Earth would be flying outwards at about 30 km/s, Jupiter at about 13 km/s. They'd have to be in just the right positions when the Sun disappeared so that their trajectories intersected in exactly the right way... too close and Earth would slingshot, too far and it would exceed Jupiter's escape velocity. And of course, the two orbits aren't coplanar, so being in the right position is difficult, maybe even impossible.

Nitpicker wrote:I wasn't thinking about whether simple or more complex kinetic models are required to sufficiently describe any of these orbits. I was thinking about orbits in terms of their kinematics only. If C goes around B and B goes around A, it is more straightforward to say C orbits B, than to say C orbits A, though I concede the latter is still true.

Ann wrote:But if the Sun disappeared, both the Earth and the Moon (and all the other planets in the no longer solar system) would just go off on a tangent, right?

Is there any chance that the Earth-Moon system would get captured by Jupiter and end up in orbit around Jupiter?

Chris Peterson wrote:

Nitpicker wrote:Well, a barycentre is often just a point in space, too. Perhaps we can agree that this is just another semantic argument over the word "orbit"? I'll concede if you will.

I'm not saying they are using orbit wrong, because it has different meanings. But since we generally think of orbits in terms of a small mass around a large one, it's easy to get confused by what a halo orbit really is. The standard equations for describing orbits don't describe anything around a barycenter, either, since the equations again assume a very large difference in mass between the two bodies, so the smaller one orbits around the center of the large one.

Anyway, whatever you want to call it, don't think it's remotely Keplerian. The path is non-planar, non-conic, and isn't around a central mass.

Nitpicker wrote:

Chris Peterson wrote:The Moon also orbits the Sun. If the Earth disappeared, the Moon would continue on an almost identical path with respect to the Sun as it is currently on.

Touche. If the Earth disappears, so does the argument.

Chris Peterson wrote:SOHO follows a complex path around the L1 point that has a 6-month period. It doesn't actually orbit that point, because there is nothing there to orbit. It would be better to say that SOHO is in a solar orbit that is perturbed by the Earth... not unlike the Moon's orbit around the Sun.

Nitpicker wrote:Well, a barycentre is often just a point in space, too. Perhaps we can agree that this is just another semantic argument over the word "orbit"? :blah: I'll concede if you will.

Nitpicker wrote:Hmmm, I like your description, too, but the SOHO site says this:
http://sohowww.nascom.nasa.gov/about/orbit.html

SOHO moves around the Sun in step with the Earth, by slowly orbiting around the First Lagrangian Point (L1), where the combined gravity of the Earth and Sun keep SOHO in an orbit locked to the Earth-Sun line. The L1 point is approximately 1.5 million kilometers away from Earth (about four times the distance of the Moon), in the direction of the Sun.