Seasons on Earth are caused by the tilt of the Earth’s axis. When the northern hemisphere is tilted toward the sun, the northern hemisphere has summer. At the same time, the southern hemisphere is tilted away from the sun and the southern hemisphere has winter. Six months later, the opposite occurs. The northern hemisphere is tilted away from the sun and winter occurs, the southern hemisphere is tilted toward the sun and has summer. Spring and autumn are the seasons of transition, or change, between the hot and cold seasons.

The year is divided into four seasons. Each season lasts one-fourth of the year. One year is 365 days long, so each season lasts about 91 days, or three months. The northern hemisphere, where we live, autumn begins on September 23. The transition from hot weather to cold weather begins.

There are seasons on Mars too. Mars is tilted on its axis like Earth. On Mars, winter will begin on September 29 for the northern hemisphere. That means the northern hemisphere is tilted away from the sun and the southern hemisphere is tilted toward the sun. The southern hemisphere of Mars is what has been in our view as Mars passed close to Earth at the end of August. Since one year on Mars is 687 days, the winter season will last for about 172 days. That’s almost 6 months by Earth time.

Because of different atmospheric conditions on other planets, the seasons can cause different results. The seasons still indicate hotter or colder temperatures like on Earth, but with different results. Because of its thin, dry atmosphere, Mars doesn’t have a snowy winter like Earth does. Mars has vast sandstorms and windstorms in its winter season. Its northern icecap gets bigger. Mars’ southern icecap disappears as summer occurs in the southern hemisphere.
Neptune, the eighth planet and one of the gas giants, shows signs of seasonal changes too. Even though Neptune is 2.8 billion miles from the sun, its tilted axis creates seasonal changes. One year on Neptune is about 165 Earth years, so each season lasts for about 41 years by Earth time.

Neptune is in its transitional seasons. The northern hemisphere is in the middle of autumn. Autumn began around 1980. The southern hemisphere is in its spring season. From Earth, the southern hemisphere of Neptune is visible. The gassy atmosphere of Neptune is showing changes in its appearance. The southern clouds are becoming lighter in color as the warming temperatures cause rising motions, condensation, and increased cloud activity.