Now, back to your regularly scheduled planetary astronomy questions. It's been a week since I've answered questions due to a massive computational fluid dynamics project I've been working on, so let's take these in order...Michael writes:
If you're standing on Mars, what star is closest to Mars' north pole?I looked up the coordinates of Mars' north pole with JPL's Horizon ephemeris generator. This is the same web form that we planetary astronomers use when we get time on a big telescope and need to know where an object is, how high up in the sky it is, what phase it's in, etc. This is a huge resource for us, so a big thanks to the folks at JPL for providing for us.
It turns out the Earth-centric coordinates currently are:
While there's no bright star right at that location, the closest one at about 7° away would be Deneb, an incredibly luminous white supergiant. Depending on which constellation scheme you go with, that star is either the head of the Northern Cross, or the tail of Cygnus the Swan.
Michael also asks:
Where's the Sun on the first day of Spring on Mars?This is a good question. For the first day of Northern Spring on Earth, the Sun is located at a position known as the "First Point of Aries", a position that by definition is RA: 0°, Dec: 0°. The math gets a little tricky if we want to do this for Mars while staying in Earth-centric coordinates of RA and Dec (some icky spherical trigonometry is involved), so let's take advantage of JPL Horizons again.
It turns out to be on the edge of Sagittarius, almost perfectly lined up with the center of our galaxy.