Expert: Tom Whiting - 1/24/2008

Question
What would occur on a planet that rotated 10 degrees per hour West, revolved 2 degrees per day West, and was tilted by 35 degrees from the ecliptic plane?

Answer
Hi  Wendy,
To be honest,  these hypothetical questions are a waste of
time....tell your instructor (and your text book) that you want
to learn about REAL astronomy....and not fairy tales.  You want to learn the distance to Jupiter  (480 million miles), Jupiter's size  (88,000 miles) where is Jupiter at in the night sky, how many moons, composition of same, etc etc.  And the same for the other 7 planets.  The distance to the nearest star, the constellations (areas of the sky), the life story of a
star, both the giants and the solar-types...REAL astronomy
stuff, and not hypothetical  "What IF".....fairy tales.

Problem with these hypothetical questions is that they
don't teach you anything because they don't exist in nature.
PLUS, there is never enough information given.....ie...
Question for your queston....When?  4.6 billion years ago
when the Solar System formed up, or today?  Or 70 million
years ago when the dinosaurs roamed?
What size of hypothetical planet?
What composition of hypothetical planet?
Circular orbit or elliptical orbit around the sun, and
if elliptical, how much ellipticity?
None of that is given, but I will infer from your title,
"Earth's Rotation" that either your textbook or instructor
is inferring...... right now.

Well, 10 degrees rotation easily gives a 36 hour day
(360 degrees divided by 10 degrees)...but that doesn't
matter....see below.

But the real killer to all life forms is that 2 degrees per day
revolution around the sun, or a "year" of only 180 days,
or 360 degrees divided by 2 = 180 day year.
(0.5 year to orbit sun once)....East or West is immaterial.....See below....
(0.5 year)....By Kepler's third law, period squared in years equals the distance cubed in AU.  
(0.5 squared is 0.25 and cube root of 0.25 is ~  0.63 AU or
an average distance from sun of 93,000,000  miles X  0.63 =
58,600,000 miles,  or roughly halfway between Mercury
and Venus' orbit is where your hypotheical planet would
HAVE to be orbiting the sun.  (Sorry, you CAN'T  keep  your hypothetical planet at the Earth's distance.....that WON'T work by Kepler's 3rd Law. )  The orbital speed is too fast
to do that!!  (Our current planet moves only 1 degree per day.)  So you HAVE TO move your hypothetical planet
much closer to the sun, 58.6 million miles IN FACT!
So you're looking at a surface temperature of well over
500 degrees F....and the axial tilt would be immaterial too,
at that close to the sun.
So we couldn't exist on a planet that close to the sun; your
hypothetical planet would look just the same as Venus
or Mercury does today,  no matter what the other conditions were.
----game, set, match-----QED.

Hope all this helps, and tell your instructor that you want
to  learn some REAL astronomy, and not friggin' hypothetical
fairy tales, and what IF's.
Clear Skies,
Tom Whiting
Erie, PA



FOLLOW UP:
Oh, and feel free to print my answer to you, and give your
instructor a copy of it!
Tom