John Carter used something called a "destination compass," which seems to have been inertial in nature.

The posting said Mercury is the only other planet than earth with a magnetic feild. unless I slept through that secret revelation in astronomy, excluding satellites, all the jovians have magnetic feilds. Hypothetically because of the liquid metallic hydrogen layer (but its still a theory.. you can't exactly dip in that far and check it imperically)... I think if I remember the theory on murcury is that it is almost entirely an iron core of a oncy larger planet, which in a hypothetical collision with a planetessimal, lost almost its entire mantle, leaving a giant iron magnet with a thin rock crust...

Neptune and Uranus have whacked magnetic fields!

there must be info on the weeb somewhere for all this though...

mmm...Dejah Thoris...

This must have been a challenging flight to plot out. You need to add a lot of velocity to get into orbit around Mercury. Something like 40 kps.

Mariner 10 trivia: This old probe was the first to use solar propulsion. Not for velocity changes, and it wasn't designed that way. The flight controllers found that they could align the craft by catching the solar wind with the solar panels.

Edited by author 03-29-2002 03:12 PM
The article is wrong. Maybe it was supposed to say 'the only terrestrial planet besides Earth...' and that was helpfully edited out at some point. Venus has no magnetic field. Mars doesn't have a global magnetic field, but does have spotty magnetic fields. The moon doesn't have a magnetic field, but there's speculation it may have once. All the Jovians have magnetic fields, Uranus' and Neptune's being particularly bizarre, with axes that don't intersect the centers of the planet, and wildly skewed to the axes of rotation. I don't think we know for sure whether Pluto has one; I'd guess not.

See the classic Nine Planets Tour.

Planetary magnetics are still a wide open field... no one's positive why planets do have magnetic fields. So no one can be positive why a given planet doesn't either.

I can't see any resources on this...anyone know why planets like Mars and Uranus don't have magnetic fields? I remember once reading that even the moon had them, albeit very weak.