The figure shows the elliptical path of a planet about the sun. The two shaded parts have equal area. If \(t_1\) and \(t_2\) be the time taken by the planet to go from \(a\) to \(b\) and from \(c\) to \(d\) respectively, then:

Consider a planet moving in an elliptical orbit around the sun. The work done on the planet by the gravitational force of the sun:

Choose the correct option:

Which of the following quantities remain constant in a planetary motion (consider elliptical orbits) as seen from the sun?
1. speed
2. angular speed
3. kinetic energy
4. angular momentum