# Calculate the orbital distance (semi-major axis) for an extra-solar planet in a 3.312 Earth-day orbit around a 1.3 solar-mass star.?

## Select one: a. 0.068 AU b. 0.058 AU c. 0.038 AU d. 0.048 AU e. 0.078 AU

Then teach the underlying concepts
Don't copy without citing sources
preview
?

#### Explanation

Explain in detail...

#### Explanation:

I want someone to double check my answer

2
May 27, 2017

The semi-major axis is 0.048AU, answer d.

#### Explanation:

The orbital period $p$ in years and the semi-major axis $a$ in AU of an orbiting body are related by Newton's form of Kepler's third law.

$M {p}^{2} = {a}^{3}$

Where $M$ is the mass of the star in solar masses.

Substituting the values and converting days to years gives:

${a}^{3} = 1.3 \cdot {3.312}^{2} / {365}^{2} = 0.000107$

Taking the cube root gives $a = 0.04748$.

So the nearest answer is d. 0.048AU.

• 3 minutes ago
• 3 minutes ago
• 4 minutes ago
• 4 minutes ago
• 34 seconds ago
• 36 seconds ago
• 56 seconds ago
• A minute ago
• A minute ago
• 3 minutes ago
• 3 minutes ago
• 3 minutes ago
• 4 minutes ago
• 4 minutes ago