network profile
| bio | website | about.sjrdesign.net |
|---|---|---|
| location | Boulder, CO | |
| age | 30 | |
| visits | member for | 1 year, 6 months |
| seen | Apr 29 at 17:08 | |
| stats | profile views | 55 |
Professional geophysicst/astronomer who also writes the blog, "Exposing PseudoAstronomy," and runs the podcast by that name.
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Jul 19 |
comment |
What will the universe look like for anyone falling into a black hole? The more I think about this, the more I'm not sure about the blueshifting. Someone please verify/correct this? |
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Jul 19 |
answered | What will the universe look like for anyone falling into a black hole? |
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Jul 19 |
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Has a human ever perished in space? You need to better-define your question. Technically speaking, "Earth's pull" lasts to the non-existant edge of the universe. Do you mean, say, the political definition of "space" which is 60+ miles? Or in Earth orbit? Or something else? |
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Jul 19 |
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Metal Dilemma: Only very few civilizations per galaxy Aaron, perhaps it's the bad Google Translate version of the article, but while it was a bit difficult to follow, I didn't see anything in it that contradicts what I stated. Maybe you could provide a better translation? I don't actually study galaxies, so I can't get much more detailed than I already did on the galactic habitable zone nor provide you with numbers that would help elaborate. Maybe someone else can? |
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Jul 17 |
answered | Is Jupiter a failed star? |
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Jul 17 |
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What is the cosmic “Axis of Evil” problem? Not related to axis of evil stuff, but you should not be referencing Journal of Cosmology. They are in no way peer-reviewed, advocate pseudoscience, and the editors have clear agendas in mind. I realize this is somewhat of an ad hominem and the article you link to could be perfectly legit, but most stuff I've read of theirs is, well, this is a G-rated board. |
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Jul 15 |
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What is so special about iron? Agreed, thanks for expanding. Guess I didn't want to get too detailed in there, other than to really give another "practical" example of why this concept is important. |
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Jul 15 |
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Would it be interesting or useful to map objects' current (predicted) locations? This is actually something I wondered during my undergrad astronomy classes but I never asked. I think part of the answer is that it's not worth doing in general because of the computation required (e.g., to do so with individual stars in a galaxy, galaxies in a cluster, etc.) and also because gravity also travels at the speed of light so the objects are affecting us from their current seen locations rather from where they "really" are today. But this is a guess on my part which is why I'm posting it as a comment and not as a full response. |
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Jul 15 |
answered | What is so special about iron? |
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Jul 15 |
answered | How does the central peak in moon craters form? |
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Jul 14 |
answered | Metal Dilemma: Only very few civilizations per galaxy |
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Jul 13 |
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Can the Hubble telescope bring any star into focus? @Joe: This all has to do with angular size (and a teensy bit with brightness when you are talking about the moon and sun). Yes, Neptune is really close compared with the Triangulum galaxy (M33). But the angular size of Neptune is 7 arcsec while M33 is 73 arcmin ... that's a difference of a factor of 600x. |
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Jul 12 |
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Universe Expansion @Warrick: The analogy is imperfect since yes, the dots do expand. The better analogy is the raisin bread one, but that doesn't illustrate quite the same thing (2D expanding in 3D). ghoppe is somewhat incorrect, though. At present, galaxies do NOT expand, as they are held together by gravity which is stronger than the expansion force. Same with clusters. There WILL come a time, though, when gravity is NOT strong enough and galaxies will actually be dragged apart by the expansion of space. Don't remember off-hand what that time-frame is, but it's at least in the billions of years away. |
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Jul 8 |
answered | Universe Expansion |
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Jul 8 |
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Can the Hubble telescope bring any star into focus? Dave, at that point it's because of how far away the objects are. See the fourth paragraph I wrote in my initial response. And when you're getting objects 10+ billion l-y away, you are not going to "see" individual stars. Individual galaxies are only going to be a few pixels across. |
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Jul 8 |
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Can the Hubble telescope bring any star into focus? @Dave: Yeah, your question was pretty vague, I tried to answer what I thought you were asking because, as asked, it didn't really make sense. To answer your question about the "zooming" process, there is no such thing on telescopes, they are at a fixed focal length (en.wikipedia.org/wiki/Focal_length) and cannot "zoom." Telescopes are constructed to look at a specific angular size - the field of view - and the field of view it's constructed with is based on the anticipated science it is trying to answer. |
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Jul 8 |
answered | Can the Hubble telescope bring any star into focus? |
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Jul 4 |
answered | Why did the ancients fail to discover that the Earth orbits the Sun? |
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Jul 3 |
answered | What is the average distance between objects in our asteroid belt? |
