Starship Asterisk*

That is not quite true. General relativity does admit warp drive solutions. Loosely speaking, they work by twisting spacetime in such a way that the speed of light inside a warp bubble "gets larger" than our familiar 299,792,458 m/s. I stand corrected. But if the speed of light inside a w...

Heard the one about the constipated theoretical physicist?

Neufer you stated no the object could not be seen if it were traveling above C. No one is going to rebut this ? Well It doesn't seem right but I’ll take it as fact then. Whether it was approaching or receding above C, I'll simply say that no known object, massive or otherwise, could travel faster t...

All that consumed spaghetti would also explain the enormous increase in mass you would suffer when approaching the speed of light.

(For clarity, I shouldn't have mentioned the term "standard astronomical reckoning" as it is irrelevant to my point, and is most likely a dated term. These days, most people consider an azimuth of zero to point North.)

The latitude doesn't really matter. If you face South (the direction for standard astronomical reckoning) the sky is the "right way up". If you face North, the sky is "upside down". Not sure where this is coming from. The astronomical convention is north up, east left. That's wh...

At what latitude does the sky turn upside down? On the equator, or 10-20 degrees....just where is the demarcation point? Thanks. really nice pic of the Central Milky Way and dust and objects... :---[===] * The latitude doesn't really matter. If you face South (the direction for standard astronomica...

I think the text is a little misleading in this entry. In the text they say, "For example, the Sun never appears directly overhead from locations well north or south of the Earth's equator." However the sun is directly overhead at the Tropic of Capricorn on December 21. I would say that t...

neufer wrote:It would read better if it said:

Faintest of the three, the much heralded Comet ISON (C/2012 S1)
is by far the closest at 14 light-minutes (1.7 AU) away.

I agree, apart from the fact that Comet ISON was only 0.3 AU closer to us than Mars at the time, according to the numbers quoted.

The "average" level of the sea has gone up and down since its formation, over millions of years. From current, more accurate measurements from the last century or so, it appears to be on a rising trend. This is partly due to the (relatively slight) expansion of the steadily warming ocean l...

Astronomy through a microscope? http://imgs.xkcd.com/comics/angular_size.png I've saved this for reference. Next time I travel to the centre of the Earth to observe celestial objects, it may come in handy. If the Earth were see-through, then from my house, I could look down at my feet, and a bit of...

The Naiads are fresh-water nymphs. Diana Nyad, if one must classify her in mythological terms, seems more like a salt-water Oceanid.

But one can still ponder the interaction between two distant galaxies, as in this APOD, with only a 19th century understanding. It still makes sense qualitatively. To a non professional astronomer, observations, for the most part, are qualitative! For galaxies and lots of other deep sky thingies, I...

Why did America mint a coin with a Martian mountain on it? Weird. Only in America.

In Dark Energy We Trust.

So you've never looked at a galaxy through your telescope? Because the actual structure of galaxies is as dependent upon the existence of dark matter as on gravity. Without dark matter, galaxies would look very different (if they existed at all). So your lack of a need to infer the existence of dar...

What’s pulling the universe apart? This is one of the biggest mysteries of astrophysics.I could state what I strongly believe to be the cause, but doing so would be “frowned upon, in this establishment.” For the record, I accept that dark energy -- whatever it is -- creates the force that is accele...

The Big Bang presumably created matter, dark matter and dark energy. And thank goodness for that, as otherwise the recent observations of the professionals would be really hard to fathom. But the real beauty is that if, at some time in the future, they observe something else they can't explain, it w...

Neufer, sounds like your Cheerio-milk-vat model of the universe is closer to common-or-garden surface tension. And here I was thinking you'd developed a Grand Unified Theory.

Very impressive APOD by the way. Very sharp for a relatively narrow field of view observed through the atmosphere.

this reminds me of a question i posed before! if gravity pulls things in, or towards then what is the equal and opposing force? it must be somthing that pushes things out, or away from it. the question i asked (i think) was: "is gravity responsible for expansion?" sounds silly but if Eins...

could the Bubble Nebula be thought of as a combination of emission and reflection nebula, covering the circular bubble and the red cloud respectively? Is this reasonable? According to some, the Bubble Nebula (NGC7635) is surrounded by a partially ionised HII region named Sharpless 162 (S162). Some ...

It seems reasonable to me, that the Bubble Nebula is primarily a molecular cloud. The stellar winds from the massive O-type star (within the molecular cloud), create the circular ionised bubble and the light from the star illuminates the remainder of the molecular cloud outside the bubble. As such, ...

After reading the caption several times, it occurs to me that perhaps [/i] the lopsidedness being alluded to, is the fact that within the nebula, there is a sparse region of space ~10ly in diameter, containing only one massive star, whilst in the cluster, a moderately larger region of space ~25ly ac...

Unless the absolute size of the nebula only refers to the little circular bubble in amongst all the red cloud. Edit: yes, that's what the link in caption says, but is not the nebula considered to be more than just the bubble? Edit again: and would you really say that the small circular bubble balanc...

Amazing photo of a spot rarely/never visible to we Southerners. However, the numbers quoted in the caption do not appear to add up (to me). The nebula (NGC 7635) is said to be both (absolutely) smaller and further away than the cluster (M52), yet the cluster appears smaller than the nebula. Are the ...