Is there life on other planets? To work on a big question, people look for hints. Some hints come from lights in the sky that people see and cannot name. Other hints come from planets that scientists study. Both kinds are worth a careful look. So we will look at the sky and at the planets, one at a time.

Let's start with our neighbor Mars. It is a small, rocky planet. It is the fourth planet from the Sun. It is about half the size of Earth. Mars looks red because there is rusty iron in its ground. Red can seem hot, but Mars is a cold desert world.

Mars once had water. Long ago, it had rivers and lakes. How do scientists know? Mars has old river valleys, deltas and lakebeds, so water most likely once flowed there. Those landforms are the evidence, and they are the reason scientists say water most likely flowed.

Rovers are robots with wheels that drive around Mars, taking pictures and measurements. As of November 2026, some of them look for signs that tiny living things could have lived on Mars long ago. A sign is a hint, and a hint is not the same as an answer. The rovers keep taking pictures and measurements to look for more.

Planets also go around other stars. A planet that goes around a star other than our Sun is called an exoplanet. Scientists use telescopes, some of them out in space, to look for them. As of November 2026, more than 6,000 are confirmed.

Which planets could hold water? That is where the habitable zone comes in. The habitable zone is the area around a star where a planet could have liquid water on its surface: not too hot and not too cold. A planet inside the zone is not too hot and not too cold.

Now look up at the sky. People sometimes report a light or a shape they cannot name. The letters UFO stand for unidentified flying object. That means something in the sky that the person who saw it could not identify at that moment. You may have heard that a UFO is a spaceship. In fact, the word only means not yet identified.

Some strange lights are reported that were something ordinary. Bright planets such as Venus and Jupiter, and meteors, are sometimes reported as strange lights. They can look like they are hovering or moving. Weather and research balloons are sometimes reported too. Balloons that fly very high often lack markings, and they can look strange from certain angles.

So what do the hints say? As of November 2026, scientists have not found life anywhere else, and the search goes on. It goes on at Mars with rovers. It goes on among the stars with telescopes. What would you look for next?

Words to know

• exoplanet: far-off planet
• habitable: fit to live
• deltas: river fans
• balloons: floating bags
• unidentified: not yet known

The short version

Mars is a cold desert world, and long ago it had rivers and lakes. As of November 2026, scientists have not found life anywhere beyond Earth. UFO means an unidentified flying object, and bright planets, meteors and balloons are sometimes reported as strange lights.

Quick facts

• Mars looks red because of rusty iron in its ground.
• As of November 2026, more than 6,000 planets around other stars are confirmed.
• The habitable zone is where a planet could have liquid water on its surface.
• UFO stands for unidentified flying object: something the person could not identify at that moment.