Star Right Ascension Declination

Aldebaran 4h 36m 16¢X 31'
Miaplacidus 9h 13m -69¢X 42'
Deneb 20h 41m 45¢X 20'
Regulus 10h 08m 12¢X 18'
Hadar 14h 04m -60¢X 24'

1.If Aldebaran is crossing your local meridian, how long would you need to wait to see Regulus cross the meridian?

2.If Aldebaran is crossing the local meridian in Saint Petersburg, Russia, what are its azimuth and altitude, in degrees?

3.At the instant when Aldebaran crosses the local meridian of Saint Petersburg, Russia, at what latitude and longitude on Earth would an observer see Miaplacidus at her zenith?

4.Which of the stars would be visible in the early evening sky (around sunset) on September 21 in Sao Paulo, Brazil?

Tut tut - this is meant to be all your own work!

you're taking the coursera course aren't you? It's supposed to be your own work I had a bit of trouble working this out but it goes as follows

aldebaran is RA 4 36
regulus is RA 10 08

all you need to do is find the difference (in numbers)between the two and there is your answer
from 4 36 find the difference to make it up to 10 ( in time sense though)
when you found that add 8 and there is the answer
example - 4 36
+ 5 32
= 10.08

so the answer is 5 Hours and 32 minutes

5 32

To answer these questions, we need to understand the concepts of right ascension, declination, meridian, azimuth, altitude, latitude, and longitude.

1. The local meridian is an imaginary line that runs from the North Pole to the celestial South Pole, passing through your current location. If Aldebaran is crossing your local meridian, it means it is at its highest point in the sky (culminating). Regulus will also cross the meridian, but since it has a different right ascension, it will take some time. The time difference between the two star's crossing is equal to the difference in their right ascensions. In this case, the difference is 10h 08m - 4h 36m.

2. To find the azimuth and altitude of a star, you need to know your location's latitude and the star's declination. The azimuth is the angular distance of the star from the North, measured clockwise, while the altitude is the angle above the horizon. Since we have the declination of Aldebaran, we can calculate its altitude and azimuth for Saint Petersburg, Russia.

3. To find the latitude and longitude on Earth where a specific star would be at the zenith (directly overhead), we need to know the star's declination and our location's latitude. The latitude of the observer is the same as the star's declination, and the longitude can be any point on Earth along that line of latitude. In this case, we need to find the latitude and longitude of Miaplacidus when Aldebaran crosses the local meridian in Saint Petersburg, Russia.

4. To determine which stars are visible in the early evening sky around sunset on a specific date and location, we need to consider the time of year, the observer's latitude, and the stars' declination. Sao Paulo, Brazil is located at a certain latitude, and on September 21, some stars will be above the horizon during the early evening hours. We need to check the declination of each star to see if they are visible from Sao Paulo.

Now, let's go through each question step by step and calculate the answers.