#Astronomy folks, my google is failing me. Is there a word for when two planets are on opposite sides of the sun?
Like, if you can draw a line through Mars-Earth-Sun then Mars is in opposition to the Sun relative to the Earth. (Right?)
What do you call it if the line is Earth-Sun-Mars?
@WelshPixie Not if I understand correctly. I think that's ANY time three bodies line up, I'm looking for specifically Earth and Mars being on opposite sides of the sun from each other.
@jessmahler Ah! Sorry, misunderstood what you were after :D I think that's just Mars Opposition?
@WelshPixie Not according to Wiki? I thought that too, but apparently opposition refers to mars being on one side of earth and the sun being on the other side of earth.
@jessmahler Was about to say conjunction but looks like other people have already said it. :D That's not specific to Earth-Sun-Mars though, just a general term from when two astronomical objects form a straight line as seen from Earth. I know in astrology they refer to it as (planet) conjunc (planet).
@jessmahler conjunct* not conjunc XD
@WelshPixie It works for what I'm doing.
Sci-fi with ship traveling from earth to Mars, needed to term for their relative positions. Probably should have given more detail in my original toot, but not wording well today.
@jessmahler Ah gotcha! :D
@WelshPixie @jessmahler
To illustrate all possible constellations of Earth with in- and out-er planets, this pic is perfect.
https://en.wikipedia.org/wiki/File%3APositional_astronomy.svg?wprov=sfla1
@jessmahler conjunction?
@applehq That looks like it. Thank you!
@jessmahler conjunction
@kiilas That looks like it! Thank you.
@jessmahler I had to look this one up, though I knew right away that "opposition" was more or less the opposite of what you were looking for.
Confusingly enough, what you're describing is "conjunction". Opposition is when a body is opposite the Sun from the point of view of an observer on Earth; so when a planet is in opposition, it's at its minimum distance from Earth for that orbital cycle.
Conjunction is when a body would be completely occulted by the Sun.
Also, a fun term for the straight-line relationship of three objects in a planetary system: "syzygy". (Also worth points in Scrabble!)
@qwyrdo This feels like it's a "frame of reference" issue. "conjunction" refers to them being on the same side, relative to the reference frame. In the case of Sun, Mars, Earth pairings, with Earth as the reference plane, it could be either Earth-Mars-Sun, or Earth-Sun-Mars. So you need to move your reference frame, in this case, really it makes most sense to have it on the Sun, then "opposition" means they are on opposite sides of the sun, and conjunction on the same side.
@jessmahler Conjunction; exterior or superior conjunction specifically if the other planet orbits inside the orbit of your own (i.e. Venus or Mercury)~
(that said I seem to have been beaten to the punch by like a bunch of people, whoops)
@jessmahler https://en.wikipedia.org/wiki/Syzygy_(astronomy) Syzygy ?