0
votes
3answers
63 views

Why don't planets give off their own light? [on hold]

Why don't the planets glow like stars, even though they consist of hydrogen and helium. For example, Mercury is 75% hydrogen and 25% helium.
3
votes
1answer
78 views

Is there a flaw with the newer purposes and correlations attributed to the HR diagram? (And would a third axis of mass correct the enclosed flaw?)

When I was younger, I was looking at HR diagrams, and began to experiment with the HR diagram. I was looking at plotting different groups of stars on the HR diagram when I found RV Tauri stars. ...
3
votes
2answers
500 views

How to calculate Longitude from Right Ascension?

Considering that a star of certain declination is crossing the local meridian at the observer's zenith at an unknown location on the earth. Here, the declination of the star is equal to the observer's ...