Final answer:
The astronomer finds a planet orbiting a binary star with a mass of 2 solar masses, completing its orbit every 4 years. Using Kepler's third law, where a3 = M × P2, and with calculations, the semi-major axis is the cube root of 32 or about 3.2 AU.
Step-by-step explanation:
Word Problem Involving Cube Root
Imagine a small planet in a distant galaxy following Kepler's third law of planetary motion, where the square of the orbital period (P) is proportional to the cube of the semi-major axis of its orbit (a). Let's say an astronomer discovers a planet orbiting a star (similar to the Sun) with a mass (M) equal to 2 solar masses. If the planet completes an orbit every 4 years, what is the length of the semi-major axis of its orbit?
To solve this problem, we use the formula: a3 = M × P2. Here, M = 2 and P = 4, so:
a3 = 2 × 42 = 2 × 16 = 32
Now, to find the semi-major axis (a), we need to take the cube root of 32:
a = ∛32 ≈ 3.2 (AU - Astronomical Units)
Therefore, the semi-major axis of the planet's orbit is approximately 3.2 AU.