Planets Do Planets Around Other

Planets

Do planets around other stars have ecliptics?

Ecliptic is the great circle representing the apparent annual path of the sun; ecliptic plane is the plane of Earth's orbit around the Sun. The other planets in our solar system also have their orbits near this plane and in the same direction of rotation as Earth.

So it's likely that other stars in the universe have ecliptics since the star- and planet-formation mechanisms are similar throughout the universe. When stars form, the leftover gas and dust accumulate by mutual gravitational attraction into planets. Observation of disk-shaped dust clouds around newly formed stars are an indication of planet formation in progress (O'Connell).

In 1999 astronomers announced the first-ever detection of an entire solar system around a star. Only 44 light-years from Earth, three large planets were found circling the star Upsilon Andromedae, a sun-like star visible to the naked eye on Earth. Again the presence of the planets was inferred from gravitational wobbling. Astronomers suspect the planets are similar to Jupiter and Saturn -- huge spheres of gas without a solid surface. One of them completely circles its star in only 4.6 Earth days (O'Connell).

Do they have Seasons?

What causes seasons? Earth is tilted with respect to its orbit. So when our North Pole is tilted toward the sun, we get summer in the Northern Hemisphere (winter in the south). When the South Pole is tilted toward the sun, we get winter. So if a planet is tilted with respect to its orbit, it should have seasons (Imhoff). The same would apply in another solar system. However,

the term "seasons" is relative depending on the distance the planet is from its star. Extreme distances from its sun may cause a planet to always experience freezing -- summer or winter.

Must they have Seasons?

If a planet has no tilt with respect to its orbit, it has no seasons. In this case, on every part of the planet, the Sun is up for half a day, then down for half a day, and day and night are equal length. At the Poles, the Sun circles around the horizon forever. At the Equator, it rises vertically at the East point on the horizon, passes directly overhead, and then sets vertically at the West point on the horizon (Seligman). These same mechanics should apply for other solar and planetary systems as well.