Airbrush

How did I miss this news about my favorite Astro mission? "....So granting Kepler at least four more years gives it a chance to look for planets in more distant orbits, allowing the telescope to survey the habitable zones of warmer stars. (It could take a hypothetical alien version of Kepler up to three years, after all, to see Earth transit the sun three times.) Seeing more transits will also increase the signal-to-noise ratio for closer-in planets, allowing more of them to be detected, researchers have said. The review committee's report did not explicitly lay out funding for Kepler's extended operations, but Kepler team members have said that it costs about $20 million per year to operate the mission at its current level." http://www.space.com/15160-alien-planet-kepler-mission-2016.html

These are good points. Uninhabited regions of Earth could be much easier to make habitable than Mars. Bases on Mars would be more for scientific exploration than a place to put people, for the next few hundred years, but after that Mars is a possible place for humans to live. If Mars could be terraformed by creating a dense, oxygen-rich atmosphere, would that atmosphere not get blown away by the solar wind in a short time because there is no magnetic field shielding Mars from solar wind?

This belongs under "Astronomy & Cosmology" which is near the top, under "PHYSICS". D H made some good points about the difficulty with colonizing Mars. I have proposed artificial gravity for bases on Mars, but I haven't heard of it. Long-term it will become an issue. The crew quarters can be along the edge of a slowly rotating centrifuge, below ground for shielding from solar wind (looks like a merry-go-round) with floor sloping down towards center of the wheel-like structure.

The difference between finite and infinite is, literally, infinite. There is no comparison. Infinite is so much greater than finite, it is infinitely greater.

Good answer D H, that's what I wanted to know. The Moon's shadow would be only 7.5% of Earth's surface. The Moon is 1/4 the diameter of the Earth, or 2,000 miles, or approx 1/16 the area. So the shadow on Earth would be approximately the same as it's size, a circle of radius 1,000 miles. Does anyone know about how wide the beam of a GRB is?

That means the universe is obviously larger than the visible universe, so we can never say where expansion began. They will say expansion began everywhere, but that is hard to visualize I must admit.

The Sun or the Moon might protect us IF they happened to be perfectly aligned with the GRB and Earth, which is a one in a Million chance. GRBs come from all angles, not necessarily from the plane of the solar system.

So it is safe to say that the Oort cloud does not protect us, at all, from a GRB. No more than a fly in the sky will protect you from sunburn.

If the gamma ray burst happened to be aligned with a giant comet in the Oort, the comet might block the GRB, but only for a fraction of a second, not long enough to save Earth from a direct hit.

I said that about a STELLAR mass black hole which has an event horizon radius of only a few kilometers. "...But, as those individual atoms fall into the stellar mass black hole, it will take a very tiny fraction of a second for those atoms to reach the singularity."

I'm at work. I can only spend a few minutes here at a time, and my work computer has no speakers. I will try to see the video at home, if I can remember.

Very interesting point. I hadn't thought of that. Since space around a black hole has a few atoms drifting around, those atoms get sucked into the black hole, and the space surrounding the black hole becomes less dense and the more dense space further away from the black hole will fill whatever void the black hole creates. So there should be an endless stream of atoms falling into a black hole, and that would be so tiny we could not detect it. But, as those individual atoms fall into the stellar mass black hole, it will take a very tiny fraction of a second for those atoms to reach the singularity. So, inside the black hole will not be a total vacuum, just much closer to it by Trillions of Trillions of times more rarified than the space outside the event horizon.

You are correct for supermassive black holes that are feeding, but for any-sized mass black holes, which are not feeding, inside the event horzon is totally void of matter, except the singularity.

All governments of the world will become more authoritarian as Earth reaches carrying capacity. Like China, there will be only one child allowed per couple. This will happen within 50 years from now. The more people there are, and the less resources, all point to less liberty. Get prepared.

What do you think will happen to atoms, or any kind of particles, inside a black hole? They instantly fall to the singularity and get shrunk to a point. I do believe that inside a black hole is totally void of matter, except the massive singularity. How could it be otherwise?

Could the only total vacuum in the universe exist inside a black hole, the region between the event horizon and the singularity?

If you could make a total vacuum, light would pass thru it. Why not?

That would be a nothing universe.......until there is a big bang.

No time or space? Any matter? If there is matter, there will be time and space. If not, nothing happens.

Good answer Joatmon! I will try to think of that.

Now that was an interesting story. I heard on the radio they were able to estimate the distance of the Earth to the Sun at 95 Million miles using the "Venus Transit Method". What is so interesting about seeing a tiny dot on the sun? This looks boring.

Light has no problem traveling through a total vacuum.

The universe is expanding into space. Space is on the other side of the expansion. Others say there is no other side of the expansion, since all of space is expanding. The universe is not pushing air away as it expands. It does not need to push anything out of the way. Whatever exists grows less dense over time. Expansion is only measured between superclusters of galaxies. Within the supercluster all matter is bound together by gravity. The universe is expanding WITH SPACE. Those are my best guesses at this time.

I saw the episode about Yellowstone on "How the Earth Was Made" and I noticed they showed there were about 10 supereruptions of Yellowstone before the last supereruption of 640,000 years ago. But they didn't say when they happened. Wikipedia only mentions the last 3 supereruptions. So I think either Wiki or "How the Earth Was Made" is wrong.

Why do you often omit a space between words? And what's with the many font changes? No big deal, I was just curious. According to Wiki the Milky Way revolves once every 250 Million years. So that is 4 revolutions per Billion years (over 16 times around the Milky Way since our solar system formed). The other stars that formed near our Sun could be scattered all around the galaxy already. I heard a scientist say that the atoms in your left hand could have come from a different supernova than the atoms in your right hand. That is how mixed up galaxies become. http://en.wikipedia.org/wiki/Milky_way