Starship Asterisk*

Happy 25th Anniversary APOD - and thank you to all who make this possible!

rstevenson wrote: ↑Fri Sep 07, 2018 1:06 am ... the light from the supernova came from an event that took place about 1500 ly from Earth, and that light arrived here at least 5000 years ago. So the supernova itself took place about 6500 years ago.

Ah - the penny drops. Thank you.

... Light from the original supernova explosion likely reached Earth over 5,000 years ago. ...While that translates to over 70 light-years (wide) at its estimated distance of 1,500 light-years, If light from the original supernova arrived 5000 years ago, wouldn't it be 5000 light years distant? Ple...

So what's hiding under the black dot on the top left corner?

Oh, this sort of 'photo' annoys me. You will never see the Milky Way like that. On a travel forum I inhabit, a poster asked something like "where can I go in New Zealand to see the Milky Way? I went outside last night (in a rural place) and could not see it." The guy was expecting to see s...

Maybe this is a dumb question, but why do meteor showers follow in the path of a comet? The physics of it eludes me. I would have thought that material ejected from a comet would disperse generally in the direction it was ejected, and continue to orbit the sun in a new orbit. I can't work out why ej...

Dare I say photochop? At sunset the camera would have to be pointing south to capture the sunlight on the clouds like that. Therefore the moon as shown would be low in the southern sky. I did not think Spain was so far north of the equator that a setting moon would be only a few degrees off the sou...

What do you make of the faint green line or streak at about 11o'clock (upper left) from the nebula? Looking carefully it seems to continue down past the LHS of the nebula.

I'm interested in knowing how a globular cluster would form... And I'm interested in how the stars in a cluster would orbit around the centre? I'm not absolutely sure what you mean here. Are you asking about the orbits of the stars inside a globular cluster?..... Ann Yes I was. Thank you Ann for po...

C0ppert0p wrote:I'm interested in knowing how a globular cluster would form...

And I'm interested in how the stars in a cluster would orbit around the centre?

Dare I say photochop? At sunset the camera would have to be pointing south to capture the sunlight on the clouds like that. Therefore the moon as shown would be low in the southern sky. I did not think Spain was so far north of the equator that a setting moon would be only a few degrees off the sout...

This picture raises a couple of questions for me - 1) I thought aerodynamics/streamlining were pretty much irrelevant for supersonic flight (or not so important as it is for subsonic flight) ... oh, I figured it out - the thing has to go through subsonic before and after it goes supersonic 2) Since ...

I like the rolling rocks idea. Gravity is low, but inertia is inertia and is related to mass, not 'weight'. Another idea is that the lines were caused by abrasion from the cargo net that was used to tow it into place during the battle between the Martians and the Europese (from the Jovian moon) (not...

What tricked me (into thinking the stones looked unweathered) is the scale of the scene. If you click on the APOD to get the original pic, it starts to make sense. The crater is 10m across, so the 'pebbles' are actually largish rocks - few seem smaller than a house brick. I expected to see a bit of ...

I think this picture is upside down.

http://apod.nasa.gov/apod/ap091005.html

The heck with the physics. Just once in my life ... someday ... I'd like to see the image in one of these pictures. ... I look for a couple of contrasting areas about eye spacing apart. In the APOD pic there are some darker patches across the middle - line up your eyes on the dark matter with your ...

A quick test with my PowerShot S2 IS indicated that it's field of view is about 45-50degrees, (a 30cm ruler filled the viewfinder at a distance of just over 30cm), so in order to take a happy snap of that 2ly wide object I would need to be about 2 and a bit ly away. The perspective would be differen...

NoelC wrote:The little streaks are most likely, as Neufer says, particle hits on the imager.....
-Noel

And if they are not? Has anyone read "Footfall" by Larry Niven and Jerry Pournelle?
http://en.wikipedia.org/wiki/Footfall

- unserious Jim

A few people have mentioned that the multiple images cannot be caused by reflections in a window because they are on the wrong side. They assume that the window is roughly parallel to the buildings seen mid foreground in the wide angle photo, and do not consider the possibility that the window might...

emc Feel the breeze at 100mph on a motor bike? Now speed your bike up to 65,000mph and feel that breeze... (Just an example ..) Mark As a matter of fact, I have felt 100mph+ breeze on a motor bike. Interesting that you should bring it up... more interesting that I am still alive, but that is anothe...

... I'm in favor of space exploration because I believe the future survival of man will be determined by his ability to find and colonize habitable planets. ... Orin I don't think finding (or making) habitable planets (space habitats) would do us much good - the population of Earth will expand fast...

They should have aired down the tires before hitting the sand. Everyone who drives a 6WD should know that.

This is not an iridescent cloud nor are water droplets responsible. It is a halo, a circumhorizon arc (http://www.atoptics.co.uk/halo/cha2.htm) produced by refraction in hexagonal plate shaped ice crystals in cirrus. Note the structure parallel to the horizon and the structured gradation of color f...

... Lastly, they're adding a docking grapple so when Hubble does die, a de-orbiting module can be launched on a cheap, unmanned rocket to de-orbit it in a controlled manner. One would think that Hubble is too important a relic to throw away - they should make every effort to retrieve it more or les...