Recent comments in /f/space

I_Heart_Astronomy t1_ja86l1d wrote

Reply to comment by ender2851 in My two year progress shooting Jupiter, using the same $300 telescope! by theillini19

Not technically, no, it just how it’s referred to when planets are visible in the sky. For the last few years, Jupiter and Saturn have been in the sky together. Even Mars oppositions have been around when both Jupiter and Saturn were around. So because of that, they were all visible around the same time of year, so it’s been referred to as a “planetary season”.

Eventually though, Jupiter and Saturn will be opposite one another for a while and thus there will be at least one major planet visible in the sky all year long, with Mars popping in every couple of years. So there won’t be a “planetary season” per se, just individual planet “seasons” like “Jupiter season” etc.

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Anonymous-USA t1_ja85s9z wrote

Reply to comment by ferrel_hadley in How big was the point of dense energy before the Big Bang? by ClassicSpurzy

To clarify, the “evidence” is actually a probabilistic analysis of competing models. The lowest model is about 137 light years across (that is the “at least” 50% larger than observable) and the largest model (“at most”) is infinite. This isn’t a mean or average of these models, mind you, just a statistical probability placing the whole universe at a likely 250x the observable 92 ly.

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hAirMoto007 t1_ja83rs5 wrote

Reply to Why are Most Meteorites Found in Antarctica? by ChieftainMcLeland

Meteorites are magnetic.... if you could put a trap to catch falling meteorites on your roof, run a magnet over them grains.... they'll all stick to the magnet🤷‍♂️

The earth is a huge magnet..... the magnetic poles are perhaps causing this situation🤔

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KingRandomGuy t1_ja82qp1 wrote

Reply to comment by Total-Oil2289 in I shot over 3600 one-second exposures to get my sharpest image of a galaxy to date by J3RRYLIKESCHEESE

It's a similar solution to lucky imaging, but lucky imaging specifically requires that your exposures are short. You can still stack very long exposures for deep sky objects and get a great result (assuming you are tracking).

The concept is similar though; in both cases you are stacking to increase the signal to noise ratio, and you should throw out bad frames.

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indrada90 t1_ja82qgk wrote

Reply to How to make a model of dark matter and energy? by Poise-on

I think the problem you're gonna run into is that we really don't know. There are certainly reasonable models available, but there is lots of disagreement, and most of them will just look like a fuzzy black ball with a galaxy inside

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Devadander t1_ja82mwr wrote

Reply to How big was the point of dense energy before the Big Bang? by ClassicSpurzy

Unknown. Current thought was a singularity, but look into the very new research published regarding black holes, vacuum energy, and dark energy.

https://scitechdaily.com/cosmological-coupling-new-evidence-points-to-black-holes-as-source-of-dark-energy/

https://gagadget.com/en/science/218939-black-holes-contain-dark-energy-that-accelerates-the-expansion-of-the-universe-and-singularities-are-no-longer-ne/

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TSotP t1_ja82feq wrote

Reply to Why are Most Meteorites Found in Antarctica? by ChieftainMcLeland

My guess, because it's huge, and permanently covered in ice, and noone lives there.

So most of the rocks found on or in the ice must have come from space, since no-one is farming or building in the area, nor have they ever done. (Unless you have read Lovecraft, in which case, I wouldn't go anywhere near those Mountains of Madness!!!)

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Chadmartigan t1_ja81qc2 wrote

Reply to comment by bustedbuddha in How big was the point of dense energy before the Big Bang? by ClassicSpurzy

Best answer, IMO. It's better to think of the big bang emerging from a state where space and time have no scale. That seems to be what our models tell us anyway. When we say things like "our models break down before the big bang," that's because at t=0, our various measurements of distance and time become nonsensical (infinite, undefined, negative when they can't be negative, etc.). You hear that state described in a lot of ways--a cosmological event horizon, an exotic form of symmetry, a singularity, and so on--but it seems to me that all those describe a state where time and space just sort of fall away.

Edit: And I'd liken the question "how big was the universe before the big bang" to "how long did the pre-big bang universe exist before the big bang?" They are kind of both senseless questions to ask about the state of the universe at that point. They both presuppose that the universe at that point had such properties, but that doesn't appear to have been the case.

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