Starship Asterisk*

Dark matter is "stuff", and as such it can clump or be otherwise non-uniform. As best as we know right now, dark energy is a property of spacetime, and has no structure. Is dark energy necessarily a property of spacetime? If so then there would be no way to accumulate or concentrate it; i...

What is the width of this scene at the distance of the galactic center?

Closer to the Sun than Neptune at the time, small, faint Pluto's position was not covered.

And of course Pluto is not a planet so it would have been inappropriate.

Klaus Doerbecker wrote: ↑Sun Dec 23, 2018 8:50 am Every child knows that the moon always shows the same side to earth. So, april, april, there will be no earthrise or movement to be seen from the moon.

"april, april" ?

Boring. A rocket is just a bus. A bit of an improvement over ancient Chinese fireworks, but that's all. Nothing very impressive about the Falcon, just a modification of dozens of other designs. Not even clear that landing the first stages will be cost effective in the long run. That attitude is sur...

It is lovely, but, "dimly", please, not "dimmly".

Well, harrumph. The name of Earth's sun is "Sol", not "Sun". ESO and APOD ought to hold the line on this.

Very professional looking. Where is the video that shows an engineering test article dropping away from a parachute, hovering on rocket power, and winching a rover to the ground?

Putting the rover under a dust cover for a propulsive landing would have been more reliable.

I prefer the MESSENGER website at the Johns Hopkins University APL:
http://messenger.jhuapl.edu/

Another curious feature visible in the full-size image is a faint diagonal jet-like streak running from a point a little below the center of the Sombrero down and right at about 45 degrees. It is apparent in the Hubble heritage (B) image http://heritage.stsci.edu/2003/28/images/p0328a_B.jpg but not ...

Which edge of that galaxy is nearer us? From the way light reflects and is scattered I think the upper edge is nearer. It would be interesting to have such details provided for as many APODs as possible, BTW. D'ohh!! Five seconds later I realize that those dark areas are shadows, so the *lower* edge...

It's heartwarming, bu we can find Happy Feet videos elsewhere. Please reserve APOD for astronomy.

Yeah, what does this have to do with astronomy? It's not even a space topic, as it is clearly an airplane and not a space vehicle. Anyway, what's important is less how much energy is used and more how much pollution, including CO2 pollution, that that energy use creates. Future airplanes will be &qu...

At a solstice, what points on Earth have day and night of exactly equal length?

http://antwrp.gsfc.nasa.gov/apod/ap071222.html