# Seeing the same stars all year

1. Oct 1, 2008

### AlexaStar

My teacher told us today that we can see the same stars in the sky all year long, but when I asked her why she couldn't answer me. She just said, "that's the way God wants it."

I would love a scientific explanation please.

Thanks,

Alexa

2. Oct 1, 2008

### mathman

Her orignal assertion is incorrect. In the northern hemishere, stars near Polaris can be seen all year round. However the stars of the zodiac can be seen only part of the year. These stars are roughly in the same plane as the earth's orbit. Those which are opposite the sun can be seen, while those in the same direction as the sun are masked by the sun. As the earth goes around the sun, which stars are hidden and which are visible change.

3. Oct 1, 2008

### Staff: Mentor

Wow, what system of education is this from? What country, what state/region, what grade?

4. Oct 1, 2008

### buffordboy23

Only some stars are visible year round. These are called "circumpolar stars.":

http://en.wikipedia.org/wiki/Circumpolar_star

There is a nice image on the right side of this link which shows how the stars "appear" to move throughout the evening.

http://en.wikipedia.org/wiki/Pole_Star

I say "appear" because the stars are actually stationary from our perspective since they are so far away. The earth's rotation is what makes the stars appear to move. Notice how there is a dot in the center of the rings. This is the north star, Polaris. If you draw an imaginary line through the earth's rotational axis it is in line with this star throughout the whole year always. As a result we see stars near Polaris in the night sky year round as well. Stars far away from Polaris in the night sky are close to the earth's orbital plane, so we can only we see them when we are on a certain side of the sun (fall, winter, etc.)

Here is a link to an activity that shows this idea:

http://www.practicalphysics.org/go/Experiment_770.html [Broken]

I am glad that you sought an answer to your question when your teacher could not provide you with one.

I wonder what her teacher would say if asked why an atom doesn't fly apart because of all of the positive charges (protons) in the nucleus. =)

Last edited by a moderator: May 3, 2017
5. Oct 1, 2008

### buffordboy23

I am very interested too. My guess is the U.S.

I guess that's the way god wants it.

Last edited by a moderator: May 3, 2017
6. Oct 1, 2008

### mgb_phys

Come November that could be the official NASA answer as well!

7. Oct 1, 2008

### Staff: Mentor

Well, except for a strip of sky that covers the sun, you can see almost all the sky available at your latitude year-round. The stars that are in the sky right after sunset are not all the same as the ones in the sky right before sunrise.

8. Oct 1, 2008

### mgb_phys

If you allow for a bit of imprecise langauge, they stars are the same all year, in that their positions don't change. It's just that the subset you can see on a particular night changes.

As for the god comment - the bell has gone, it's been a long day, there's a coffee waiting in the teachers lounge and an annoying little know-it-all (like me!) is asking questions!

9. Oct 1, 2008

### Staff: Mentor

:rofl: [*cleans coffee off of monitor*]

10. Oct 8, 2008

### chemisttree

Maybe she was referring to the stars in the sky at either of the two poles...