Please help with these questions, and use appropriate amount of sig digits?

1) An observer is on the right place on the Earth to see the Moon directly overhead at midnight on a given day. Where does that observer see the Moon in the sky one day later at midnight? (Marks:2) Hints: (i) the Sidereal Periods of the Earth and Moon are 365.25 days and 27.3 days (ii) drawing figures showing the positions of the Earth and the Moon on the two nights can be very useful

2) A planet is seen at Greatest Eastern Elongation on June 1 in a given year. The next time it is seen in Greatest Eastern Elongation is on June 1 of the following year. What is the Sidereal Period of the planet? (Marks:2)

3) A comet is observed to have an orbit with a perihelion distance of 0.5 A.U. and an eccentricity of 0.980. What is the aphelion distance of the comet's orbit? (Marks: 2)

4) The spectrum of a star is recorded (i.e. observed). The "rest wavelength" of the "Balmer alpha" spectral line of hydrogen is 656.279 nm. If the radial velocity of the star is 40 / towards the observer then what wavelength is observed for the Balmer alpha spectral line? (Marks: 4)