Recent comments in /f/space

DudeWithAnAxeToGrind t1_jdldx34 wrote

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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ufhrzdgug t1_jdlak7c wrote

A 1 kilometer long bridge has to "bend" about 78 millimeters to follow the shape of the earth (simplified). A one meter stick 0.0078 millimeters. Do you think you can see such a small difference?

One could ask why the level of the ocean is not going down after removing a glas of water. It went down, but the change it's too small to see.

You can remove a grain of sand from a beach. There is less sand now but would anybody notice?

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Fleaslayer t1_jdl8x1t wrote

Here's a picture of a billiard ball under a microscope. We see it as really smooth, but magnified it actually has mountains and valleys. If the earth was shrunk to the size of a billiard ball, and you could hold it, it would be much smoother than a billiard ball.

So, okay, at the scale we interact with it, it has mountains and valleys and flat spots. Even so, it's pretty easy to see the curvature of the sphere. When you're at a high cruising altitude on a plane and look out at the horizon, it's curved. When you stand on the shore and watch a boat sail away, it starts looking like it's sinking as it goes over the horizon, over the curve.

It's a sphere, it's just (to us) a really big sphere.

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kuro24811 t1_jdl8pil wrote

Surprisingly it is the first for the US, but NASA has brought comet dust back with the Stardust Spacecraft. https://en.m.wikipedia.org/wiki/Stardust_(spacecraft).

NEAR Shoemaker was a fun mission to read about also since it surprised people at NASA when they tried and successfully soft landed on the asteroid Eros at the end of the mission since it wasn’t designed to do that. https://en.m.wikipedia.org/wiki/NEAR_Shoemaker

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OnlyAstronomyFans t1_jdl88od wrote

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.

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