Starship Asterisk*

Does the disk spin like a galaxy, where particles along arbitrary spokes from the center all move with the spokes, or is it like a liquid swirling around a drain, where particles spiral into the black hole?

D'oh! I forgot about expansion. Folks posit that empty space expands at about 16km/s/Mpc, To explain the evacuation motion of 260km/s, the very empty Void must be some 45 Mpc across. Phew! Thought I had to get smart on a new force. As to why expansion exists, like Mueller said, it is beyond our purv...

The repulsive push by the Local Void... In the quantum world, there is no such thing as "empty" space. Experiments seem to verify the Casimir Effect. Particles mysteriously appear and annihilate. Does all this teeming activity account for the repulsive push by the void? Nuclei contain Hig...

Be proud! Be very proud!!

That is the shadow of a man standing on the moon.

How are all these distance measurements made? Why the discrepancies? Hubble sez: 1800 light years https://www.spacetelescope.org/images/opo9738c3/ https://cdn.spacetelescope.org/archives/images/thumb700x/opo9738c3.jpg ESA sez: Jupiter's Ghost lies some 3000 light-years away http://www.esa.int/spacei...

That is an interesting thread to the right of Sgr C. I wonder, what is exciting those threads?

Iksarfighter:

https://upload.wikimedia.org/wikipedia/ ... 9.full.jpg

Maybe we could add a camera configured for night viewing. I'd like to see thunderstorms from above, maybe catch sprites, elves, and jets, so elusive and difficult to study.

Hereby nominated for APOD!

This must drive folks with strong magnetoreception to distraction. As the Earth cools (title of my favorite soap opera) the 1/2 Gauss field weakens. Before we get exterminated by the solar wind, could we set up a series of geostationary satellites to create a 0.1 Gauss electromagnetic field to suppl...

I meant to refer to the awe-inspiring image of the day. If the shadow is oval-shaped when viewed from above the axis of rotation, that would violate Einstein's gravitivity. If we use the angle of the jet, which must be the same angle from which we view the accretion disc, unless black holes wobble, ...

Is this image the first proof that a black hole exists at the center of Messier 87 and perhaps most, if not all, galaxies?

Hubble visual image of Messier 87: https://upload.wikimedia.org/wikipedia/commons/thumb/0/07/Messier_87_Hubble_WikiSky.jpg/250px-Messier_87_Hubble_WikiSky.jpg Earth-wide radio telescope array image M87's black hole: https://upload.wikimedia.org/wikipedia/commons/thumb/a/af/Black_hole_-_Messier_87_%2...

She's a witch!
Which?
The one riding the broomstick!
-Excerpt from "Close Encounters of the 42nd Kind"

It's easy to see how the Earth-centric folks were baffled back in the good old days, when burning Galileo's books seemed like a smart idea.

Judging by the inbound trajectory, if the orbit is changed at all, it would be slightly closer to the Sun on the way out. Looking at the Mars-Earth-Sun plane, Sliding Spring comes in from above left and will return below left. It might be slightly closer to 1 Mars Astronomic Unit, but the change wou...

Will Siding Spring be visible from Earth without a telescope, or will it be a dot next to Mars? Re: That Reddit discussion, methinks you might say that every star is the center of galaxy, since we really don't know where the boundary is. A star 14 billion light years away could be just as far from t...

If you encounter a cross-site-scripting error trying to watch the flash movie at pbs.org, there is a 720p copy at
https://www.youtube.com/watch?v=4-3ZmNF35sw
where you will also find lots of space-related NOVA episodes.

(Better check your lepton count. Are you still glowing?) I did not know that sprites propagate downward. Do elves behave in the same manner? Lightning storms remain mysterious. Allowing for the permittivity of wet air, there isn't enough of a charge differential to account for ground strikes. Charge...

...Not to mention the green glow of high-altitude chemoluminescence. Although the location is far enough north to catch Kp5,6 auroras, they would present themselves as a red glow on the horizon, much like the prior APOD from Payson, AZ.

Thanks, Geckzilla! Can't tell the players without a program.

The thin nature of the rings is indeed enhanced by this equinox image. In the full-sized image, you can see three (or more) moons, mere specks compared to the large lunar APOD of a couple of days ago. The rings are indeed quite wispy, a fact usually hidden in Earth-source images. How something that ...

The term, 'life', does not necessarily imply bipedal humanoids with opposable thumbs and gifts of speech and the written word. Paramecia may be a bit of a stretch, perhaps amoebae or oxygen-breathing flora? The Endorians, for example, may communicate via psychic channels, thus finding us too silly t...

I'd keep the lander away from the snow. An undisturbed bit of charcoal may be safe from geysers. Can't tell if the holes are sleeping geysers or collisions. Depending upon where the geysers appear, this comet could start tumbling. Hope the harpoon is strong enough to account for the changes in accel...

What would a Monet painting look like if he wore corrective lenses for his near-sightedness? Ruben?