Are constellations and moon in about the same position in the sky, from one night to the next, say at 10PM?

Question

if I see the big dipper from my front porch one night at 10PM, and it's about 60 degrees above the horizon, should I expect to see it at 10PM the next night at about 60 degrees above the horizon, also?

Answer 1

Yes.

The constellations are about 3 minutes and 56.55536 seconds earlier each day in arriving at the same position in the sky as the previous day. This is not very noticeable in 24 hours to the naked eye. If you look at the same place in the sky tomorrow at the same time, it will still look almost the same. The change in the moon's position is a different story.

However, the moon can be an hour or more behind where it was yesterday at the same time in the sky. This varies slightly because the distance to the moon can vary by about ±31250 miles during its orbit.

Generally, the moon is approximately 12 to 15 degrees later each day on the average.

For example, the geocentric equatorial longitude of the moon at 00 hr dynamical time on 8 Aug 2006 is about 298.1105971°

On 9 Aug 2006 at the same time, the moon's longitude is about 313.4700234° - which is a lag of about 15.35942°

Since 15 degrees = 1 hour, this means that on the night of the 9th the moon will be about 1 hour behind where it was the night before at the same time.

However, the stars cross their same location in the sky by about 4 minutes earlier each night, which will not be nearly as noticeable as the change in the moon's position, which moves in the opposite direction from west to east each day.

The constellations change their positions very little from night to night, but the moon changes much more noticeably.

You wouldn't easily notice the change in the Big Dipper from one night to the next, but over a couple of weeks it would surely be noticeable if observed at the same time each night.

Answer 2

No, they will move from night to night, especially the Moon. The Moon orbits the Earth once every 28 days so it moves by about 1/28 of the way around the sky each night. The Earth orbits the Sun once a year so the constellations move 1/365 of the way round the sky each night. You need to watch the stars for several weeks to notice the change easily, but the Moon changes position dramatically each night.

Answer 3

The star constellations move slightly day to day, night to night, for the observer. Over the course of the year, they change every day. The paths change as the Earth travels around the sun. Since the Earth is tilted on its' axis, the relative position changes. As far as the moon goes, its' position changes more as every day it advances 1/28 of a revolution around the Earth. When the moon is full, it is in the West at sunset. 14 1/4 days later it is in the East in the morning. The geometry is complex, but books and charts are available to explain where the stars, constellations, and the moon are during the coarse of a year.
Good Observing!

Answer 4

Moon moves quite a bit each night but the constellations have to be watched night after night to notice the seasonal variations as the Earth pivots on it's axis.

Answer 5

If you watch, it takes the moon about 50 minutes longer each day for the moon to arrive at the same spot in the sky where you saw it the night before. This is caused by the Earth's rotation combined with the revolution of the moon around the Earth.

See these web sites for more information:
http://www.astronomycafe.net/qadir/q1038.html
http://www.wcer.wisc.edu/ncisla/muse/earth-moon-sun/outcomes/EMSconcepts.html
http://moonsighting.com/faq_ms.html
http://www.ucolick.org/~bolte/AY4_00/week1/motions.html
http://aa.usno.navy.mil/data/docs/RS_OneDay.html

Answer 6

The stars are in a slightly different position from one night to the next, because as days pass, we orbit farther around the sun to a different view of the universe.

The difference in the moon's position and its shape (what phase of waxing/waning it is in) at the same time as the previous night may not be THAT noticeable from one day to the next, but, say, if you look three days later at the same time, you'll see a noticeable difference in position and shape. Then a day comes in the moon's cycle in which it moves from your seeing it at night to your seeing it in the early daylight hours.

Answer 7

About the same...but they obviously have to move a little more each night as we orbit the sun. There are 365.25 days in a year, so each day or night we have advanced a little more around the sun. I highly recommend buying a copy of Astronomy Magazine. (At least ONE copy.) I did this many years ago, and I have been subscribing to it even since. You will learn a LOT and the pictures are unbelievably cool.

Answer 8

Yes, I love to look at the sky at night. My favorite constellation is Orion, followed by the Big Dipper.

Answer 9

i would take into consideration the parallax effect... since the moon is moving around the earth, and the earth around the sun, the point of refference is constantly moving. so i could would have to say, that they are never in the same position, never twice since the beginning, and, also take into consideration, that the stars are also in movement.