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awarded  Nice Question
Apr
18
comment Were there any images of a transitary event of Jupiter or Saturn as imaged by a deep probe mission
I doubt that any flyby spacecraft had a camera which could image the Sun and descern an occulting planet on its disc. They were designed to image dimm objects on the background of empty space.
Apr
12
comment If “9 th planet” is ejected by Jupiter or Saturn, why does it have a very far perihelion?
Great answer! i) formed like that in a collapsing gas cloud turning into an open star cluster sounds like the most doable scenario. That the Sun has divorced its family but still carries dynamic traces of it. Maybe narrowly escaping becoming binary.
Apr
12
comment Why do planets move in an elliptical orbit?
Isn't the eccentricity an illusion of our frame of reference? Wouldn't orbits be circular if spacetime didn't bend, but gravity was instead an electromagnetically attractive force? A marbel dropped on a rubber sheet with one through deforming it, will move circular from one perspective, but elliptically from another. Or am I wrong about this?
Apr
12
comment If “9 th planet” is ejected by Jupiter or Saturn, why does it have a very far perihelion?
Sorry for my ignorant comment, but I'd guess it must've had two major disturbances, perhaps one interstellar. The formation and ejection of a fifth gas giant, larger than Nine (plutwo:-)) fits some simulations. Maybe that event brought something intersting about.
Apr
9
comment Can the expansion of spacetime be directly measured with laser interferometry (like GW can)
@pela Doesn't all spacetime everywhere expand and accelerate? Is it not a matter of sensitivity to measure it at ever shorter distances? If different regions or directions of spacetime expand differently, then a LIGO-like concept might catch it? If space expands equally in all directions, then there is no reference, right? But what about time with its single direction and constant speed.
Apr
9
comment Is Io's orbit or rotation affected by its volcanism?
@zibadawa timmy An eruption means that the inner of Io cools. Where does that energy go?
Apr
9
comment Is Io's orbit or rotation affected by its volcanism?
@zibadawa timmy First the eruption causes a reaction force on the moon. Then, the ejecta impacting around the volcano should give another push in the same direction. While flying, the ejecta has a gravitational pull on the moon in the opposite direction, but the impacts might cause heat and outgassing. Since it has no atmoshpere, I would think that eruptions push Io even though the ejecta falls back.
Apr
8
comment Can the expansion of spacetime be directly measured with laser interferometry (like GW can)
@Rob Jeffries Well, maybe they don't ;) Couldn't the increased redshift be detectable? That would be a very different instrument thoug. Is the LIGO precision tech transferable to other instruments?
Apr
8
asked Is Io's orbit or rotation affected by its volcanism?
Apr
8
asked Can the expansion of spacetime be directly measured with laser interferometry (like GW can)
Apr
3
accepted How was precision astrometry done before digital imaging?
Apr
3
asked How was precision astrometry done before digital imaging?
Apr
1
comment Is it possible that Mercury was originally the moon of Venus after a giant impact?
I would speculate that the heavier elements in Mercury fits better with it having formed close to the Sun, than as the smaller fragment having caught the heaviest parts of Venus. The Moon is pretty low density. And I can imagine problems with impact debris reforming to a planet, not around Venus, but far away in heliocentric orbit. But little is known about both objects. M is hard to reach and V is hard to survive on.
Mar
30
comment Would being ejected from the Milky Way Galaxy have any major impact on life on Earth?
(Controversial?) physics professor Svensmark has suggested that Earth might undergo climate changes on a galactic scale as it orbits the Milky Way. Different regions have different intensity of stellar winds which affect the magnetosphere of Earth and the formation of clouds. A vagabond Solar System would not have that. (I just love the idea of us having a galactic weather!)
Mar
30
comment Could mirrors be replaced with CCDs?
The photons are sent from the celestial object. Why re-send them? Is the data loss from reflection maybe too small to be a priority problem?
Mar
30
comment Could mirrors be replaced with CCDs?
@SkyGuide How come glass knows where a photon comes from, when no CCD or electronic sensor we manufacture can?
Mar
30
comment Could mirrors be replaced with CCDs?
I still don't get it why stupid silicon in glass as a middleman is better for the photons than the smart silicon in electronics in which it finally ends up in before we can interpret it. Let the CCD have the same shape as a primary mirror would've had, if that helps, and register the photons electronically instead of simply bouncing them.
Mar
29
comment Could mirrors be replaced with CCDs?
@Donald.McLean Why not capture all the photons directly, why play ping pong with them?
Mar
29
comment Could mirrors be replaced with CCDs?
Bigger is better, but couldn't semi-intelligent electronics de-diffuse the photons better than a stupid geometrically reflective surface can? How is it better that a photon from a distant galaxy hits a silicon atom in a mirror before it hits, and is electronically recorded, on a silicon atom on a CCD or similar light sensitive device? Just like all the points on a mirror can produce a focus, I suppose that with some math (not my job), a CCD array could do that too.