Recent comments in /f/space

ChrisARippel t1_j669ogv wrote

Reply to comment by Varsect in If you could instantaneously place a space telescope at any desired distance (LYs), from any planet/galaxy etc., where would it be and what would you be documenting? And for what purpose? by kennyarsen

Observations from the space telescope would be looking to disprove isotropy from that location. If the space telescope doesn't disprove isotropy from that location, this is at least partial confirmation. Similar to Eddington's 1919 eclipse test of Einstein's Theory of Relativity.

Milky Way may well be invisible to the space telescope, but other galaxies may well be visible from both directions.

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AurumArgenteus t1_j661up1 wrote

Reply to If you could instantaneously place a space telescope at any desired distance (LYs), from any planet/galaxy etc., where would it be and what would you be documenting? And for what purpose? by kennyarsen

Assuming it can communicate back even for an a few moments, the inside of a black hole. Assuming it cannot, probably inside a nebula at that age where rocky planets can begin forming. And assuming the comms are bound by physics, choose one of the interesting moons NASA and others aren't going to.

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WictImov t1_j65rdv4 wrote

Reply to comment by cousgoose in If you could instantaneously place a space telescope at any desired distance (LYs), from any planet/galaxy etc., where would it be and what would you be documenting? And for what purpose? by kennyarsen

I don't think using a black hole as a gravitational lens would achieve your objective. A simple lens like a magnifying glass does not work like a set of lenses with well-placed relative distances like a telescope (or microscope). Try using a magnifying glass to see something in the distance. It doesn't work, it will only focus on something closer to it than it is to your eye.

This is all moot however because you would see those things with more clarity if you placed the space telescope close to them, to begin with.

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AsherKendrell t1_j65rcag wrote

Reply to Why are "metals" more effective at cooling molecular clouds than hydrogen and helium? by Thomas_Bonk

The primary way molecular clouds cool is by emitting the energy of the heat as light, which can escape the cloud.

A hot cloud of gas means there's lots of atoms and electrons zipping around, bumping into each other. If one of those bumps gives enough energy to an atom's electron, that electron gets excited to a higher energy level. When that excited electron jumps back down to a lower one, it emits the energy difference as light. Hydrogen and Helium are very simple atoms, meaning they only have 1-2 electrons to excite, few energy levels to excite to, and the minimum energy you need to make that first jump is higher. Conversely, "metals" have many more electrons and much more complex energy level structures with smaller, easier to accomplish jumps. Molecules, such as H2O, CO2, etc even more so. Therefore metals and molecules are much more likely to be able to take the energy of thermal collisions and convert it into outgoing light.

Take a look at these spectra for a visual: https://images.nagwa.com/figures/628134219594/1.svg

Each vertical line corresponds to one possible electron transition in the corresponding atom. You can imagine collisions as randomly firing along these spectra, and only when they hit one of the lines does light get emitted. So you can see, for H and He you're going have a way harder time getting hits. (And, in real life your shots aren't uniformly spread either, but skewed towards the red side at the temperatures molecular clouds are typically at. For hydrogen, you'd only have a single target to try to hit, vs the forest of lines that nitrogen has for example)

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SaishDawg t1_j65r3ph wrote

Reply to If you could instantaneously place a space telescope at any desired distance (LYs), from any planet/galaxy etc., where would it be and what would you be documenting? And for what purpose? by kennyarsen

I would say our best candidate for a planet with intelligent life. That’s cheating though since we don’t have one (maybe life, but no signs of intelligence yet). The center of the galaxy (outside its black hole) would also be fascinating to pan around what must be a dizzyingly different night sky.

You do have the separate problems of getting any information back home (in a reasonable time at the speed of light) and potentially power (could we ever get a signal from current technology telescopes we place really far away)?

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