the sun - Procession of the Equinox

The sun does not orbit another star. A star, even a very small brown dwarf, would have been seen, if not in visible light then in the infra-red by the WISE survey.

However there is no mystery about precession. The Earth is non-spherical, it is wider around the equator, and because the Earth is tilted with respect to the ecliptic, there is an asymmetry in the force of the sun, and the moon, on the Earth. This force pulls the axis of the Earth's rotation in a circle. The basic maths of this is not so hard, and is in the Wikipedia page on Axial precession. This explanation of axial precession was known to Newton. There is nothing controversial about it.

The sun does orbit the galaxy it takes about 230000 years to complete one orbit. This has nothing to do with axial precession.

The page you link to is worthless. It offers an "alternate explanation" of a phenomenon that is very well understood, and pretends that there is some mystery, where there is none. It the uses this to justify a lot of astrological nonsense.

To repeat.

• There are not "many theories" explaining Axial precession.


• Axial precession is a well understood phenomenon, due to the Earth not being a sphere and the axis of the Earth not being perpendicular to its orbit


• The sun does not orbit another star. We know this because we could have seen it.


• No astrology based on the presence of another star is valid.

orbit - Where is Luna 1?

It currently is orbiting the sun, on an orbit that takes 450 days. It is an orbit that takes it close to Earth's orbit, and so is not stable in the long term. It may eventually collide with the Earth, but perhaps only after many thousands of years. It is not functioning (it doesn't have any way of generating power) and is pretty small, much to small to be picked up in Earth telescopes. We don't know exactly where it is now.

X-ray flare questions - Astronomy

I search the reference papers about flare, but nobody said something about below clearly. Could anyone give some help?

If a single X-ray decay without eclipse or other irrelevant factors is not able to fitted well by an exponential decay, can we say it is not a flare?
Can exponential decay be a criteria? Could somebody specify a flare with a weird shape or non-exponential decay? How large is the decay index (e**(-tau)) tau acceptable?

What kind of ratio(rising time/decay time) is acceptable?

If we cut a timing series of a flare into several parts, can we tell whether they are from the same flare by their X-ray spectra ?

spaceflight - How would FTL travel appear through window of ship?

Star Treck's warp drive assumes being able to establish a warp bubble around the space vessel to move slower than light in the local space, but faster than light in the surrounding space, to work around the limitations of special relativity.
A warp bubble would show some similarity to a worm hole. To get an idea of spacetime distortion caused by a wormhole you may like to watch some of the videos the University of Tübingen (Germany) is hosting.

The same site provides a simulation of a walk through the city with just below the speed of light.

In both cases you get visual geometric distortions.
But you get changes of the color by the relativistic Doppler shift, too, as simulated here.

When travelling faster than light you would get additional strange effects, depending on the method you overcome the speed of light barrier.
One well-known effect is Cherenkov radiation caused by charged particles travelling faster than the speed of the light in the medium, which may still be slower the vacuum speed of light. Vacuum speed of light in a flat spacetime can only be achieved by massless particles like photons.

Particles moving faster than the vaccum speed of light (tachyons) have been hypothesized, but have not yet been found.

Overcoming the speed of light would resemble somewhat falling into a black hole. When faster than light, light cannot reach you from the back. So this region would look black.

Travelling faster than light in a medium is physically feasible, at least for subatomic particles. Travelling with the vacuum speed of light or faster leads to serious problems, with the exact vacuum speed of light being the biggest challenge, since you either need to get rid of your rest mass, if travelling in flat space, or you need to warp spacetime. The latter needs huge amounts of energy causing devastating damage to the environment.

coordinate - Finding a location using the direction of shadow, UT and date approximately

Does anyone know how to find a location by using :

1. the direction of shadow relative to the normal (for example azimuth
   angle)


2. the Universal time (UT) and date

I have a satellite image and I know north, time and date. One of the cues that I can use is, for example, in the northern hemisphere the direction of shadow is north.

Would anyone know if it were possible, and how, to calculate the location based on these parameters?

the sun - What do we mean by Sunrise and Sunset?

Sunrise is the moment when the point you are located on, on Earth, gets to receive its part of the sunlight (due to the Earth's rotation you spoke about). And sunset is the moment when the point you are located on, on Earth, has made its turn and faces away from the Sun, then preventing you from receiving its light.

When the Earth will have made another half of its rotation, you will get to see another sunrise.

The Earth makes a full rotation in a 24h cycle. This is why you get a sunrise and a sunset everyday :)

space - Can an asteroid have a molten core?

Yeah, entirely possible.

There are a couple of examples of asteroids that we've identified which may have, or recently had, molten cores. 21 Lutetia is a notable example. Vesta is another.

The main issue is that because of their size, the ratio of surface area to volume is higher than the average planet. This means it cools much faster. So while some may have molten cores, they won't stay that way for as long as a planet might. Additionally, most aren't very near large gravity wells like a moon might be, so they don't have the same tidal forces adding energy to their interiors.

All this makes it less likely to find an asteroid with a molten core, but it's not impossible.