Recent content by ScottVal

Ah, interesting points, by "Sun die" I assume the Sun will still be there, it'll just be much different. It will be a red giant and it may envelop both the Earth and the Moon and they would be absorbed into the Sun, and the Moon wouldn't have a chance to get to the Roche Limit. Or the...

Yes, thanks for the link. It is also interesting that, although the "face" of the Moon we see is always the same, due to the tidal locking of the Moon relative to the Earth, there are small changes in the look of the Moon's face due to librations. I was also looking at an article about the...

I figure lunar features, through a telescope, look just a bit larger at perigee. I understand that comparing perigee to apogee is like comparing quarter to a nickel. It's not a huge difference. I'm not going to take my telescope out every night, so I like to choose the best nights.

So I guess a perigee quarter-Moon would be a kind of astronomers' super Moon!

OK, thanks. I was thinking that the best time to look at the Moon through a telescope would be when it is at perigee; pretty obvious, eh?

Hello- I was looking at a table of the dates of lunar perigees for 2020, and I noticed that most of the perigees were between 27 and 29 days apart. So the perigees do not appear at a constant frequency, which I did not expect. There are even a pair, between June 30 and July 25, which are...

Hello, We hear a lot about gravity-assist, which usually means using a planet like Jupiter to speed a spacecraft on its way to another destination, like Pluto. But what about using a moon of a planet as a reverse gravity-assist? For example, if you wanted to place a spacecraft in orbit...

I think I see now, that the implication is not that there is an "edge" to the universe 92 billion light years away (which wouldn't make sense), but that the "observable" universe seems to be bounded by a sphere 92 BLY in radius, simply because of the age of the universe, etc. Thanks.

Hello- I just watched (or tried to watch) a YouTube video by Fermilab, in which the speaker states that the universe has a definite "width" of 92 billion light years. I could only watch about half of it because more and more terms were used which it am not familiar with. Besides, his pedantic...

As I mentioned in an earlier post, the question of the universe's center (which it does not have), may also lead to the question of whether or not the universe has (or could have) an "edge." I believe this is related to the balloon analogy, that you could in theory move in any direction (or...

phinds, thanks for the answer to my query. I guess it follows, if the universe has no center in terms of space, it also would have no "edge" in terms of space. The microwave background is like a spherical wall around us, with a radius of 14 billion light years. This gives credence to the idea...

This discussion also begs the question of whether or not the universe is bounded in the sense of space (as opposed to time). I.e., does it go on forever, in all directions? -Scott V.

Yes, thanks. Also, maybe another way to look at it is that the universe has always been unbounded, contrary to an uninformed belief that the universe started at a point, or a little sphere. So at one time, when the universe was very young, the universe consisted of this unbounded plasma. Then...

OK, thanks for the answer! I guess one way of looking at it is, in the young universe, space as we think of it now didn't really exist, or quite exist as much as it does now, so all around us are the remnants of that early universe?

When a "layman" hears of the cosmic microwave background, and this layman also has a passing knowledge of big bang theory, it can be difficult for said layman to wrap his head around what the CMB really is. That layman might ask, wouldn't this primordial radiation have "passed" us by now, and...