Is there life on other planets? As of November 2026, scientists have not found life anywhere beyond Earth, and the search goes on. Scientists use telescopes, some of them out in space, to look for planets around other stars. They also send robots to another planet and search for life with a radio telescope. Each tool can answer one small question, and together they show how a big question gets worked on, one careful step at a time.

One place to look is Mars. It is the fourth planet from the Sun, about 142 million miles (228 million km) away on average. Mars is a small, rocky world, about half the size of Earth. Its air is thin and is mostly carbon dioxide, nitrogen and argon. It is a cold desert, and its ground holds rusty iron, which gives the planet its red color. A day on Mars lasts 24.6 hours, very close to a day on Earth.

Mars did not always look like this. It has ancient river valleys, deltas and lakebeds, so water most likely once flowed there. Liquid water is essential for life as we know it. As of November 2026, some Mars rovers look for signs that tiny living things could have lived there long ago. A rover is a robot with wheels that drives around Mars, taking pictures and measurements.

Curiosity landed on Mars on Aug. 6, 2012, and explores Gale Crater. As of November 2026, its finding is chemical and mineral evidence of past habitable environments. That does not mean life was there. It means these were places where microbial life could have lived. A place that could have held life is not the same as a place that did.

Perseverance launched on July 30, 2020, and landed on Feb. 18, 2021, in Jezero Crater, a crater 28 miles (45 km) wide. As of November 2026, its goals include seeking signs of ancient life and collecting rock samples for possible return to Earth. Its search is for signs of ancient life, and the word signs matters. A sign is something to study, not an answer.

A planet that goes around a star other than our Sun is called an exoplanet. NASA has confirmed more than 6,000 of them as of October 2026, out of billions believed to exist. Some are rogue planets that orbit no star at all. One way to find one is to watch a star for tiny dips in its light when a planet passes in front of it, which is called a transit. Another is to watch for a star that wobbles, because the gravity of an orbiting planet tugs the star back and forth.

Once a planet is found, scientists ask whether it is in the habitable zone. This is the area around a star where a planet could have liquid water on its surface: not too hot and not too cold. Habitable zones are also called Goldilocks zones, because conditions are not too hot, not too cold, and liquid water is essential for life as we know it.

The SETI Institute is a nonprofit that searches for life beyond Earth. Its Allen Telescope Array is the first radio telescope designed from the ground up to be used for SETI searches. As of November 2026, scientists have not found life beyond Earth, and the search for it continues.

People also report strange things in the sky. The letters UFO stand for unidentified flying object: something that the person who saw it could not identify at that moment. In 1947, businessman Kenneth Arnold said he saw nine fast objects near Mount Rainier that moved "like saucers skipping on water." A newspaper wrongly described them as saucer-shaped, which gave us the term flying saucer.

The U.S. Air Force began Project Sign in 1948. It was followed by Project Grudge and, in 1952, Project Blue Book. Early investigators thought the objects might be Soviet aircraft, while some researchers suggested spacecraft from other worlds. From 1947 to 1969 the Air Force investigated UFO reports. Of 12,618 sightings reported, 701 stayed unidentified.

Some reports have ordinary causes. Bright planets such as Venus and Jupiter, and meteors, are sometimes reported as strange lights because they can look like they are hovering or moving. Venus is the brightest object in the night sky after the Moon, and it appears as a morning star or evening star. High-altitude balloons often lack markings and can look strange from certain angles. Secret high-flying planes in the 1950s and 1960s caused many reports. A strange light is something to check, and a report is where the checking begins.

Words to know

• exoplanet: far-off planet
• transit: passing in front
• habitable: livable
• rover: wheeled robot
• unidentified: not yet named