I'm pretty sure the sun doesn't rotate at the same speed as the earth, so since we rotate around it as the year goes on I'm fairly certain we see every side of it every year.

Sorry, I didn't make that clear. I'm not talking about seeing the other side of the Sun. I mean seeing the space behind the sun.

We see it every 6 months, that's why constellations change depending on the time of year

Sorry, i get what you mean now. There are plenty of craft that can see what we cant from earth

Ok, I'm still not making this clear. If an object is in the exact same orbit as Earth but on the opposite side of the sun while moving at the same speed as Earth, we would never see it. That is the blind spot I'm talking about.

Like STEREO-A and B? https://www.nasa.gov/mission_pages/stereo/main/index.html

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We would be able to measure how other things interact with it. But we have space craft like the Parker Solar Probe, So we do know what on the opposite side to us

Yep, just wait a day then you can see that space.

There are picture of probes looking back on earth from various locations in our solar system. Depending on the location you could see the space behind the sun. looking back at earth 🌍

Are you talking about the Earth Sun Lagrange 3 point? Always opposite to the earth relative to the sun. I did some research online and couldn’t find any record of us observing it. Don’t get your hopes up though. L3 is gravitationally unstable. It is likely that nothing is there besides a weird bend in gravity.

This was the plot of the movie Melancholia. There was another Earth on the same orbit as ours, but we had no idea because it was always on the exact opposite side of the Sun ftom us. Until something happens and the two worlds are set to collide.

I don't have an answer to your question though, sorry.

I would THINK even if we didn't have visual confirmation, we might be able to detect an object in other ways. Asteroids making weird turns because of the gravity or something.

We used to call the notional "opposite planet" by the name Nemesis. Pretty sure it's not there.

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???? What are you talking about? Why something would be exactly at the opposite side of the sun, relative to earth? Nothing has the same speed, mass, gravity, etc to make this event possible. Are you contemplating the possibility that there’s something hidden behind the sun?

> This was the plot of the movie Melancholia. There was another Earth on the same orbit as ours, but we had no idea because it was always on the exact opposite side of the Sun ftom us. Until something happens and the two worlds are set to collide.

That's... not it at all.

Melancholia was a rogue (planet not in orbit of our star or any other star, but flying freely through the galaxy) gas giant (not another "Earth") that entered the solar system without being noticed at first because it entered on the other side of the Sun.

The collision happens because Melancholia enters into Earth's orbital path as it's coming through the solar system - not because it was "always on the same path."

He’s going on about the twin earth theory where there’s a second earth on the exact opposite side of the sun in lockstep with our earth so in theory we would never know what’s there unless we just leave a satellite hanging around somewhere that isn’t in a orbit around earth like mars or something

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I understand that now, but we wouldn't need a satellite(even if we have many now). We'd know by the way other objects/planets interact with it

Obviously he is talking about sneaky aliens, duh.

I assume that. Our own solar system has planets that differ A LOT in size, speed, orbit, material composition, etc. I think it’s more plausible to find aliens in mars than another planet hidden on the other side of the sun.

I believe OP is trying to describe seeing what is on the other side of the sun, at any given time, from the vantage point of earth.

To essentially see “through” the sun to observe what an earth bound viewer can never see.

Yes, the STEREO mission (Solar Terrestrial Relations Observatory) was a pair of satellites launched into solar orbit in 2006, one going slightly faster than the Earth, one slightly slower, so that over years they move to the opposite side of the Earth's orbit from us and are able to see the "back side" of the Sun. STEREO-B (Behind) died in 2014, STEREO-A (Ahead) is still operational.

By a funny coincidence, as you're asking this question now, STEREO-A has almost completed its first "lap", and is coming back past the Earth this summer. So it can't currently see what's going on on the other side of the Sun because it's got almost the same view we do.

https://stereo.gsfc.nasa.gov/ https://stereo-ssc.nascom.nasa.gov/where.shtml

There's also the Parker Solar Probe and the ESA Solar Orbiter, which are currently making tight elliptical orbits close to the sun, which bring them to the "back side" once every few months. Right now the Parker probe is pretty close to the far side of the Sun from us, and the Solar Orbiter is between us and the Sun.

http://parkersolarprobe.jhuapl.edu/The-Mission/index.php#Where-Is-PSP https://www.esa.int/Science_Exploration/Space_Science/Solar_Orbiter/Where_is_Solar_Orbiter_Track_ESA_s_Sun_explorer

To clarify, this refers to two spacecraft that are parked at the L4 and L5 Lagrange points. As you can see in the link, from those points you can clearly be able to see anything orbiting in opposition to Earth (approximately, but not exactly, at L3).

In fact, there are no objects at L3, according to... top... men.... [Always cite your sources, gang!]

I think op means the area of space directly behind the sun. The answer is yes. We rotate around the universe on several axis. The parts that we can’t see are based on the north or the south hemisphere but if you had the ability to go anywhere on our planet, you could see in all directions around the universe, and during certain times of the day and certain times of the year someone able to go to anywhere on our planet would be able to theoretically see in any direction into the universe. I hope that helps. It was hard for me to explain without drawing pictures.

Oh yeah. Something could hide directly on the opposite side of the sun from us, but probably not from a spacecraft in a trailing earth orbit, especially if it trailed further than like one earth radius

I understand the question. But how and why?

Haven’t you ever been tryna sleep and some apparently world changing thought enters your mind?

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This is the Counter-Earth hypothesis. Wikipedia has a nice section on how we would be able to detect any such planet.

And according to Marvel Comics cannon, the High Evolutionary built Counter-Earth, but placed it out of phase in time with the rest of the universe so it would be undetectable. 😄

Yes, there are several probes that could (and those that are still active can) see that region of space. Plus any spacecraft that left Earth-Moon system, and had capabilities to take photos as it flew to other planets in the Solar system (or to the Sun itself).

No, there isn't anything there. Several reasons. L3 Lagrange point of Sun-Earth system is there. L3 is unstable point, nothing could hide there for very long, it'd fall out of orbit relatively quickly. Earth is a planet, meaning its gravitational influence is strong enough to clear its orbit of other stuff. This includes stuff attempting to orbit on the opposite side of the Sun from us. I.e. anything in Earth's orbit either gets stuck in one of the two stable Lagrange points (L4 and L5; there's some dust and couple of asteroids stuck there), captured into orbit around Earth (becoming a moon, but so far no luck for capturing that 2nd moon), or eventually flung out.

And as several people mentioned already, even without being able to see, we'd be able to detect gravitational influence of anything sufficiently large, like another planet. In case you were asking if there could be something large (e.g. planet sized) hiding there, the answer is resounding no. Even if there could be something large out there (which it can't, orbital mechanics simply doesn't allow it), we'd figure it out back in the 19th century by simply observing trajectories of other stuff that we can see, long before we started launching stuff in space.

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That is the well published intergalactic approach vector when observing primitive species such as Earthlings.

Any probe would be able to see it, it just needs to be not in the same orbit as earth, so even juno or, messenger, cassini and any of the probes on mars would be able to image it. Many of them have taken pics looking back.

There is no other side. Sun and earth aren't tidally locked. Sun rotates at its axis once every 27 days. It's actually 25 for centre and 30 for axis as sun is a big ball of gas. This is very well observed with solar cycles and sun spots. Earth and Moon are tidally locked.

we see "the back" of the sun about every month since that's about as long as it takes to make a full rotation.

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It is also the plot of the 1969 UK film Doppelganger (called Journey to the far side of the sun in the US). The opposite earth in the film is also opposite in everything being a mirror image of our earth. The film is watchable, but it is certainly no 2001 and the plot is very pedestrian.

https://www.imdb.com/title/tt0064519/

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The idea is a weird one it would be extraordinarily coincidental for two planets to be locked in the exact same orbit path in different phases.

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Oumuamua saw the other side and bounced.. 100k light year quarantine zone confirmed

Hello u/Dave-C, your submission "We can't see on the other side of the Sun. Have we ever used satellites to see the other side?" has been removed from r/space because:

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Thank you. I get that it was a stupid question but thanks for answering something that intrigued me :)

Really? Whoopsie.

I guess I'm thinking of something else. I thought there was like a 2nd Earth where everyone had a doppelganger.

I've never seen this, but this is exactly what I thought Melancholia was about. I was wrong.