Can someone give me a list of all seasonal constellations by season?

Question

I have searched the net but each list differs.

Answer 1

http://www.onr.navy.mil/Focus/spacescien...

You have the seasons there, and some pictures too. Hope they're useful.

Answer 2

This is a great question, but hard to answer as just a list.  Fortunately, it's not too hard to figure out.  I have seen lists of things to see by season for the Northern Hemisphere.   For example, "Half-hours with the Telescope" is available for free on Gutenberg.  (I estimate 3 hours per "hour" for an experienced observer.)

It depends on where you are on the Earth.  In Michigan, where i live, you can see quite a few northern constellations year round.  For example, Ursa Minor (the little dipper) has the North Star in it - it never sets. But other constellations, like Ursa Major (with the big dipper - or the Plow to some) never sets.  So it's constellations to my south that are seasonal.  Some farther southern constellations, like the Southern Cross, never rise.  But if you go far enough South, the Southern Cross never sets.

The thing to do is get a list of constellations with their RA and Dec. Dec is declination in degrees from the celestial equator.  If you're 42 degrees north, then anything farther north than that never sets.  But things farther south than (42 - 90) = -47 degrees South never rise.  So constellations between those values rise and set.

But they do it every day of the year.  So what makes them seasonal?  It depends on when you want to look at them.  We'll assume that you never want to look at a constellation when the Sun is up.  That cuts out half the day.  I like to look in the evening.  And this is where the RA (Right Ascension) comes in.  It's measured in hours - 24 hours just like the clock.  We conveniently have 12 months.  So the sky shifts by 2 hours of RA every month.  If you start at January, objects with 0 hours are overhead at midnight.  So in July, month 7, constellations with an RA of 14 are overhead at midnight.  But i like to look a little earlier.  So i add two hours.   So in July, month 7 -> (7 * 2 + 2) = 16.  If the number goes over 24, just subtract 24. And at 10 pm at the start of July, Scorpius is due South.  Scorpius has an RA of about 16.

Answer 3

There is no definitive list. It depends on your location (not just which hemisphere) and the time of night.

In the northern hemisphere, we view Orion as a winter constellation and Cygnus as a summer constellation. But Orion is rising at dawn in August, and Cygnus is rising at dawn in January.