Can the sun rise from the west on Earth?

[selfAdjoint]

No because they move so much faster than the Earth in its orbit. Now on the backside of the Sun, when they are moving in the opposite direction to the Earth, they would appear to be moving backward, but at those times they are invisible to the naked eye.

 

[nrqed]

No because they move so much faster than the Earth in its orbit. Now on the backside of the Sun, when they are moving in the opposite direction to the Earth, they would appear to be moving backward, but at those times they are invisible to the naked eye.

Are you sure of this? Venus has such a small apparent magnitude (i.e. it is so bright) and a fairly large maximum elongation (about 46 degrees) that I am almost certain that retrograde motion of Venus can indeed be observed with the naked eye.

Notwithstanding the issue of naked eye vs telescopic observations, it is still a fact that *all* the planets (inferior and superior) exhibit retrograde motion.


Coming back to the original poster, maybe a source of confusion is that books often talk about the motion of the sun from west to east when talking the motion *relative to a fixed background of stars*.

(Now I am addressing anyone who is interested, not necessarily selfAdjoint who probably knows all that).

The idea is that the Sun and the planets (and the stars) and everything rise in the East and set in the West over one day, but the Sun and stars don't quite move at the same rythm. The Sun takes 24 hr to get back (roughly) to its initial position whereas the stars take a bit less (about 23h56m). This is simply due to the revolution of the Earth around the Sun. Anyway, people then say that the Sun therefore moves *eastward* relative to *a fixed background of stars*. This means that if you plot the position of the Sun along the zodiac signs, you will see it moving eastward, accomplishing a full circle in one year. The planets do the same thing except that they sometimes revert directions, hence retrograde motion.

I just hope this might be a bit helpful.

Pat

 

[K.J.Healey]

Just a quick question. Does the sun rotate about its center? Relative to a distant observer of course, say another star.

 

[tony873004]

Just a quick question. Does the sun rotate about its center? Relative to a distant observer of course, say another star.

Yes, the Sun takes about 25 days to rotate once around its axis, relative to the background stars. It's still a mystery as to why the Sun rotates so slowly.