This is a very vauge question as it could refer to anything from the surface of the sun, to the Earth, to many things beyond the sun.
1) if by sphere you mean the sun, then the closest layer is that is not part of the sun is the plasma sphere.
2) if by sphere you men the Earth layers, then the Exosphere is the closest.
3) if by sphere you mean a body that is large enough to be considered a planet, the answer is Mercury, since the other bodies in the area maybe closer but they are not large enough to be sphere shaped.
the sun is sphere with moon rocks allowing it to be bumpy
the sun is a sphere
The sun is a sphere and the moon is a sphere.
Mercury is the closest planet to the Sun
Mercury is closest to the sun
No. The planet closest to the Sun is Mercury.
Mercury is closest to the sun.
Earth is what even not closest to what not the Sun?
The closest planet to the sun is Mercury.
The planet closest to the sun is Mercury.
the chromosphere
NO! its a sphere