Astronomy | Astrophysics Answers

For a special mission to Mars you need to know the smallest distance between Earth and Mars.
However, you have lost your astronomy book and you could only find these values:
Distance Earth to Sun: 149.6 million km
Orbital period Earth: 1.00 years
Orbital period Mars: 1.88 years
By using these values and assuming that Mars and Earth move an circular orbits, calculate the
smallest possible distance between Earth and Mars.

The Moon has a mass of M = 7.3 · 1022 kg, a radius of R = 1.7 · 106 m and a rotation period of
T = 27.3 days. Scientists are planning to place a satellite around the Moon that always remains
above the same position (geostationary).
(a) Calculate the distance from the Moon’s surface to this satellite.
(b) Explain if such a Moon satellite is possible in reality.

You have discovered a new star in the Milky Way: Your new star is red and has 3/5 the tempera-
ture of our Sun. The new star emits a total power that is 100,000 times greater than the power
emitted by our Sun.
(a) Determine the spectral type (i.e. spectral classification) of the new star.
(b) How many times bigger is the radius of the new star compared to the radius of our Sun?

Difference between the density bounded medium and the picket fence model

Calculate the magnitude of the faintest object that can be detected by an optical
telescope of diameter 5.0 m.

Define an active galaxy. What is the source of its activity?

Why is it difficult for LyC radiation to escape galaxies with high star formation rates?

What is the difference between the density-bounded medium and the picket fence model?

(b) What is the difference between the density-bounded medium and the picket fence model?
(c) Explain the spectral shape of the perforated shell model (see article: figure 1, right box).
(d) What is the Sunburst Arc and how was it discovered?

(b) What is the difference between the density-bounded medium and the picket fence model?
(c) Explain the spectral shape of the perforated shell model.
(d) What is the Sunburst Arc and how was it discovered?