# Tag Info

37

I do disagree with the other answers, not on the result, but on the reason. You don't need to go faster than the speed of light to pass through multiple stars in a few seconds. Putting aside the problems of accelerating to a high enough speed in a human lifetime without being crushed by G forces, storing enough fuel for that (what would you use as fuel? ...

13

Surprisingly, yes, for some of them. Small, old stars can be at room temperature ex: WISE 1828+2650, so you could touch the surface without getting burned. Any star you can see in the sky with the naked eye, however, would be hot enough to destroy your body instantaneously if you came anywhere near them. An article about cold stars: https://www....

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Edit: added some more details on the scientific method. KIC 8462852 is unusual. It exhibits dimming, but unlike other variable stars this dimming follows an irregular pattern. Several hypotheses have been proposed to explain the star's large irregular changes in brightness as measured by its light curve, but none to date fully explain all aspects of ...

12

No. While none exist to date it would be possible for a dead star to have cooled to a safe temperature. However, such objects are inherently supported by degeneracy pressure--they're very dense. Very heavy & very dense = very high surface gravity (typically 300,000+g.) While you're not burned you're squashed. The low mass limit for a brown dwarf is ...

9

As you rightly point out in your question, Canopus star trackers are pretty nifty instruments. I don't think it's really possible to do them justice in a single post, so I'll include a few summarizing points here and will include links to other articles, etc. for more information. 1. How do they work? NASA Technical Report 32-1559 does an excellent job of ...

8

While this animation is somewhat misleading as the wavelength line seems to be following the position of the exoplanet as it passes the star, I think this is an example of Exoplanet Spectroscopy. Simply put, scientists measure the light output from a star. When an exoplanet passes between the star and our observation point, the total light level drops. This ...

7

Yes. They did see stars. Here is an excerpt from the Apollo 11 Transcript. 02 23 59 20 CDR: Houston, it's been a real change for us. Now we are able to see stars again and recognize constellations for the first time on the trip. It's - the sky is full of stars. Just like the nightside of Earth. But all the way here, we have only been able to see stars ...

6

TAI conceptually is time measured by a perfect atomic clock running exactly at the geoid. There are some issues with this concept: A perfect atomic clock does not exist. Older and presumably less accurate atomic clocks are regularly replaced with newer and presumably more accurate atomic clocks. Few, if any, atomic clocks are at sea level. Mean sea level is ...

6

Modern star trackers are intentionally a bit out of focus. This spreads the light from a single star (which would otherwise resolve to a single pixel) across multiple pixels. Close binaries are similarly spread across multiple pixels. This is a feature rather than a misfeature. What about stars that happen to appear to be close by one another, resulting in ...

5

This answer will make some assumptions (which I will state explicitly as much as possible) and simplify things, but it should give a rough explanation as to why detecting extraterrestrial life is difficult. Now, we can, of course, use the Drake equation (and all of the assumptions therein) to make a rough estimate of how many civilizations there might be in ...

4

It helps to suppose that you're flying your ship somewhere closer to a galactic nucleus than we are. Sure, the nearest star to us (after the Sun) is several light years away, but if you get within a few light-years of the center of the Milky Way, the average distance between stars is less than 0.02 light year (1/250th of what other answers are taking as the ...

3

They are found in the Gliese Catalog of Nearby Stars. This kind of naming is nothing new, you may have seen NGC objects (listed by their entry in the New General Catalog). There are a lot of catalogs.

3

You might be touching a piece of one right now. Heavier elements, like gold, are formed when massive stars undergo a supernova at the end of their lives. During this gigantic explosion they fuse elements together to form heavier ones, which then get scattered out into space as dust, which eventually coalesces under gravity, forms a planet, and with a bit of ...

3

The Dyson-sphere is gravitationally unstable. The planets have a circular orbit, but a the Dyson-sphere is a sphere. Where could it rotate? It doesn't matter, on the poles it would fall into the star. The current technological reality is that the fusion energy, and then heating and lighting a planet with it, is not far from being possible. We could do in ...

3

In the Earth Centered Inertial frame (ECI, often called EME2000), a spacecraft could indeed pass through the Z-axis (formed from X=0 and Y=0). However, as with all orbital dynamics, it would not remain in that position unless there was active thrusting. It is possible for a spacecraft to stay in close proximity of the Earth's pole (north or south) with ...

2

Yes, via a light-speed U-turn When traveling at speeds close to the speed of light, stars appear to conglomerate into a single blurb in front of a spacecraft (artistic example). When slowing down, those stars will appear to move back to their 'normal' rest positions, and diminish in spectrum (i.e. they will appear to undergo redshift). This means that stars ...

2

The outer layers of a red giant or supergiant star are, although hot, extremely tenuous. For instance VY Canis Majoris has an average density of a few $mg$ per cubic meter. It might be possible to dive through the outer parts of the star on a hyperbolic orbit and escape before your spacecraft picked up enough heat energy to be a problem. If you could do that,...

2

Yes, that event was roughly 1mln years ago. At scales of "merely" a million light years, the inaccuracy would be of order of 10 days. On distances of billions of light years the inaccuracy can climb considerably due to space expansion - an event we have observed today, that ocurred a couple billion years ago, occurred a considerably shorter time ago than ...

2

There are a number, usually broken down into 3 parts. I've included the 3 parts below, and a database where one might find information about these objects. Extra-solar objects- SIMBAD Solar System Objects- JPL Ephemerides Satellites- Either JSPOC or Celestrak

2

The Boötes void is 330 million light years in diameter and is known to contain only 60 galaxies. If these were evenly distributed across the centre of the void (which they are not) they would be 5.5 million light years apart. Being distributed through the void the spacing would be very much greater. So there are places where there are no galaxies for ten ...

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Asking for no light at all is a stretch. But an important component within our Solar System is where no sunlight reaches. Crater bottoms at the Moon's North Pole have a confirmed presence of water ice, permanently shadowed from the sunlight that would otherwise vaporize it.

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We can tell how hot a star is by its colour, and (at least in some cases) how far away it is by how it appears to move in the sky as the Earth goes around the sun. We know how bright it is by direct measurement and we know how much light an object at that temperature emits per unit area. From these four numbers we can solve for the size of the star. More ...

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I find the Satellite spotter on in-the-sky.org to be very useful for this. According to that site, at 9pm last night (23 Oct 2018), no ISS passes or other bright satellites would have been visible from the Miami area. An old Delta II rocket stage would have been visible around 8:20pm, just about as bright as the ISS sometimes appears.

1

It depends on whether you are approaching or leaving that star. Light undergoes blue shift if the source of light is moving towards the observer (equivalently, if the observer is moving towards the source) and red shift if the observer and source are moving further apart. The equations are not particularly simple for velocities approaching that of light, ...

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