2
$\begingroup$

From what I understand Earth's L3 is obscured by the Sun, so is that true for our viewpoint of the other planets? Or, are there times when other planets are on the other side of the Sun from Earth and we can see their L3 position? For the Hilda's of Jupiter have we observed them in that position or is it that we have calculated their coordinates to be in the L3 position?

$\endgroup$
1
  • $\begingroup$ L3, unlike L4 and L5, is not particularly stable; I wouldn't expect to find much there. $\endgroup$ – Keith Thompson Apr 4 '15 at 2:38
2
$\begingroup$

You asked

L3 is obscured by the Sun, so is that true for our viewpoint of the other planets?

No. Each planet orbits with it's own period because each planet is at a different distance from the sun. So most of the time we can see the L3 point of each planet's orbit from Earth. Occasionally it goes behind the sun from our point of view.

For the Hilda's of Jupiter have we observed them in that position or is it that we have calculated their coordinates to be in the L3 position?

The Hilda family do not occupy the Jupiter L3 point. They generally orbit closer to the sun than Jupiter, and orbit three times for every two orbits of Jupiter. Their orbits are interesting; they have eccentric orbits (up to 0.3) that in some cases cross the orbit of some of the Trojans. You may have noticed that some of the Hildas also approach the Jupiter L3 point. At that point, and when other members of the family approach the Tojans at L4 and l5, the Hildas are moving more slowly. So the Sun's gravity gradually accelerates them, pulling them back to the lower, faster part of their orbits.

I have linked to the Wikipedia Hilda family page. The Lagrangian point page is also helpful.

$\endgroup$
1
  • $\begingroup$ I appreciate the clarification about the position of one of the groups of Hildas, and their interaction with the Trojans, the links are great, and that we can see L3! $\endgroup$ – AOC Apr 6 '15 at 2:45

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.