How come we can only see one side of mercury?

Question

Ive heard only one "face" of mercury is visible from earth, but how so if it spins around?

No sarcastic answers please

Answer 1

It used to be thought that Mercury was locked facing the Sun, but that is not the case---it actually revolves so that one day on Mercury (from sunrise to sunrise) is about 180 days.  This is not "locked" to the period of the Earth's orbit, and so it isn't true that we see only one side of Mercury.

Answer 2

Because Mercury is nearer the Sun than our planet, we can only see it as a crescent or gibbous (more than half but less than full), because when its fully lit side is facing us, it is behind the Sun and cannot be seen. This is called superior conjunction, and when it is between us and the Sun, it cannot be seen as its dark side is towards us. This is called inferior conjunction. When Mercury is near superior conjunction it is gibbous, when it is near inferior conjunction it is a crescent. Mercury can be seen either just before dawn or just after sunset, near the horizon. It is too near the Sun for it to be safe to look at it through a telescope.

Answer 3

No this isn't the case.

Answer 4

I think the question you should be asking is: "why do we only see one side of our Moon" ? Is it hiding something on the other side that they don't wont us to see or is it just by chance ? Personally speaking, I think our Moon is the most mysterious object in the Solar System & have you ever wondered why we have never been back there (providing we really did go in the first place that is !) ?

Cheers !

Answer 5

The same reason we only see one side of the moon.

Answer 6

The reason we dont see its 'full' face is that, when she is on our side of the sun, there isnt any light shining on it to reflect to us. And when she is at the back, obviously the sun is in the way. You cannot use the suns bright light as an excuse for not seeing the planet, but the lack of any incidental light, except star light, is pretty compelling reason.

We can of course image it by Radar and could use laser to build up a picture. But 'SEE' is usually used for vision by eye. So thats my excuse

Answer 7

you're wrong.

mercury's orbit and rotation are related, so we see similar things at similar times. but since its so hard to see anything on mercury (have a look some time), ppl concluded they were seeing teh same thing all teh time.

Answer 8

It isn't true, really.  What is true is that, from Earth, Mercury is pretty hard to see.  The glare from the Sun makes it very difficult. I've seen Mercury naked eye a couple times, and in binoculars a few times.  The sky is never really dark before it sets. So, for a long time, people thought that Mercury was tide locked to the Sun - with one side facing the Sun forever.  With RADAR, it was discovered that Mercury rotates 3 times for each 2 of it's years.  So one side faces the Sun, then the other side faces the Sun in alternate years.

When Mariner flew by Mercury, it managed to image about 45% of the surface.  The current MESSENGER mission has already expanded on that, and when it enters orbit, it should image the entire surface.