Starship Asterisk*

"A milliarcsecond is a thousandth of an arcsecond."

Thanks, Chris.
I was going too much by sound and too little by brain.
But maybe, at 75, it's forgivable?
Peace and health,
Phil G

"I was also wondering about the signification of mas... Charon about the same as Betelgeuse?? I don't think so" [My apologies for not knowing better how to handle quotes.] A milli-arc-second [one millionth of one arc-second, I assume] is an angular measurement. Think of looking through a s...

Thank you all.
You have successfully made me feel much more significant
Peace,
Phil

Question:
When the distance sun to earth is listed, is that surface-surface or center-center?
Thanks

Just from looking at a few photographs of this phenomenon, I get the impression that the cone-shaped "nebula" is nothing at all. By that, I mean it looks like the trailing "void" left behind a star plowing into and through the massive dust cloud. If it were a nebula, then it woul...

apodman,
Thanx. That makes much sense.
Peace,
Phil G

OK, it's only a co-opted drawing; no problem with that.
But am I correct in assuming that, the farther out you go
from the sun, the narrower and denser, therefore more
conspicuous, the Milky Way would appear?

Pete,
Thanks. Now it makes sense.
Phil G

The text speaks of a circle having a radius of x# degrees. I find this very confusing. In my career in land surveying, degrees were units of angular measurement, and the radius was a linear measurement. Would someone kindly explain how a radius can be measured in degrees?
Peace,
Phil G

I have seen the little Digg sign at the bottom ot the APOD, but since there are no instructions or any other information about it, I have simply ignored it.
It seems to me that, if you want people to use something for your benefit, you ought to let them know how.
Peace anyway,
Phil G

1] The process for searching the memberlist for your own [or any] user name is most tedious, esp. not being able to select a page number between 3 and 500. It would take a long time to get to page 274, for example, if that's about where you thought the info might be. 2] How does one go about changin...

I wonder if dense star clusters, such as M55, might be the remnants of a [probably much smaller] galaxy that the Milky Way absorbed [correct terminology?] many millions of years ago.

I notice that many of the craters have smooth centers and others have a "mount" in the center. Any guesses why the difference? One, center left, looks like it has a steep-sided depression, almost conical, which makes me think it can't be from a subsequent impact. Interesting, to say the le...

To over simplify the point, A Planck's Length is the smallest measure of distance, 1/2 of a Planck's Length does not exist. My non-scientifically-trained mind is having trouble with this. I presume that Planck's Lengths are mathematical units. Correct? [It's not in my dictionary.] If that is so, th...

Infinity means without boundaries. It is said there is no edge of the universe (no boundary). So, by definition, isn't it infinite? Not necessarily. The universe can be 'boundless, but finite'. A decent two-dimensional analogy is the surface of a sphere. It has no boundary (you can never encounter ...

Empirical measurements of the universe are meaningless if the universe is infinite. May this non-scientist ask, Why? If the "Whole" cannot be measured, how can a "Part" be measured based on the same measuring criteria? I don't understand this. It sounds like: We can't measure th...

One: I'm fully aware of the definition of infinity, infinity is simply no limit. Two: That isn't any definition of infinity I've ever encountered. One: Let's hear your definition of infinity if you don't like mine. From Merriam-Webster's 10th Collegiate [not a scientific] dictionary: infinity noun (...

capt.yesterday wrote:i want to know why nothing can travel faster than the speed of light?

My unscientific guess would be that no scientific measurement of anything else has been found to exceed that speed. Perhaps the problem lies in the way the "fact" is stated.

In endless UNIVERSE [Steinhardt & Turok; a Christmas present so don't blame me ;-) ] I read: "...the WMAP image painted on the outer layer appears to span an enormous area, a spherical surface 13.7 billion light-years in radius." [p.27] The APOD explanation under the picture has the sa...

> It should generally be safe enough to assume that oppositions and conjunctions refer to objects as seen from Earth, and with respect to the Sun, unless otherwise stated. <
Chris, Thank-you for this. The obvious is so often overlooked simply because it is so obvious.
Phil G

Chris, Your note seems clear, but it contradicts what Ms. Layton of Astronomy Magazine says. It also gives a good example of the need for specific references. To say two celestial objects are 180 degrees apart, is only valid when the point of observation [or, reference point] is cited. Any two objec...

NoelC,
And as soon as I posted my reply, I looked at yours and saw the "opposite" pun. Please forgive an old man for being so slow on the up-take.
Phil G

NoelC, Thanks for the help, but I'm still confused. I can understand [now] that there are 2 kinds of opposition. The problem, as I see it, is that folks only say "opposition" without specifying which they mean. I tried the link to wikipedia, but gave up after about 4 minutes since all I go...

I based my question on the information quoted below. Phil G Opposition is a geometric alignment of Earth, the Sun, and a planet. This alignment occurs when Earth is on one side of the Sun and the planet is directly on the other, or opposite, side of the Sun. Regards, Laura Layton Associate editor As...

> Explanation: Very good telescopic views of Mars can be expected in the coming weeks as the Red Planet nears opposition on December 24th. Of course, opposition means opposite the Sun in planet Earth's sky - an arrangement that occurs every 26 months for Mars. Because of Mars' more elliptical orbit,...