The asteroid belt. There is not enough gravity to hold the gases in place during the hottest part of the day. The part that overlaps is the part that we see illuminated from Earth at any particular phase. By using triangulation and observing the nearby stars from different positions along Earth's orbit we can calculate the distance to the object with simple geometry. On the H-R diagram there is a slightly wavy line of stars that runs diagonally down from left to right.
Most stars are on that line.
The Main Sequence. The star is bigger. At the end of the Sun's life, what type of star will it become and where will it be located on the H-R diagram. These are located in the bottom left corner of the H-R diagram. The plane of the Moon's orbit is tilted by 5 from the plane of Earth's orbit.