How Many Planets Are There?

The U.S. space agency NASA recently announced that 6,000 planets have been found outside our solar system.

NASA/Goddard Space Flight Center

An artist created this image of some of the exoplanets that have been discovered so far.

Eight planets orbit the Sun, but how many planets are orbiting other stars? The U.S. space agency NASA recently announced that 6,000 planets have been identified outside our solar system, with many more discoveries on the horizon.

Scientists first identified an exoplanet (a planet outside our solar system) in 1995—just 30 years ago. Since then, improved technology has enabled them to find planets faster than ever. In fact, just three years ago, the total number of confirmed exoplanets was 5,000. Today, scientists are studying 8,000 more space objects that they believe to be exoplanets. And the hunt for planets is far from over. NASA says it’s likely there are billions of planets in our galaxy alone!

NASA/JPL-Caltech

This image shows some of the telescopes that have been used to find exoplanets. The telescopes are operated by different organizations, including NASA, the European Space Agency, and the Canadian Space Agency.

But scientists are already learning a lot about planets by studying the ones they know about. For example, our own solar system includes four rocky planets, like Earth, and four gas planets, like Jupiter. But overall, it looks like there are more rocky planets than gas planets in the galaxy.

By studying planets and their traits, scientists may be able to determine whether there’s life on other planets. Planets that are similar to Earth are most likely to be able to support living things.

“Each of the different types of planets we discover gives us information about the conditions under which planets can form,” said Dawn Gelino, head of NASA’s Exoplanet Exploration Program, in a statement. Gelino said NASA wants to find out “how common planets like Earth might be and where we should be looking for them. If we want to find out if we’re alone in the universe, all of this knowledge is essential.”

NEWS EXTRA

Indigenous Peoples’ Day

October 13 is Indigenous Peoples’ Day in the United States. It’s a day to honor the history, the resilience, and the many cultures and traditions of Indigenous peoples. (In the United States, Indigenous peoples are also called American Indians or Native Americans.)

Indigenous Peoples’ Day is the second Monday in October, the same day as Columbus Day, which has been a federal holiday since 1937. One reason for this is to recognize that American Indians were in the Americas for thousands of years before Italian explorer Christopher Columbus landed there.

One way to observe Indigenous Peoples’ Day is to learn more about Indigenous peoples. There are hundreds of American Indian tribes in the United States. Each has its own history, culture, and traditions. So, where should the learning begin? One idea is to start where you live. If you’re in the United States, find out which Indigenous peoples live or lived where you now live and learn about their history.

A chef smiles as she stirs food in a bowl as food cooks on a grill. — Chef Sherry Pocknett, of the Mashpee Wampanoag, at work in her restaurant Sly Fox Den Too.

Two people of the Mashpee Wampanoag in traditional dress dance at an outdoor event. — A Mashpee Wampanoag woman dances with a member of the public at an Indigenous Peoples’ Day event in Massachusetts.

Seven men in headdresses stand on the ice in front of a crowd in an arena in front of the words Indigenous Celebration. — Representatives from First Nations tribes including the Siksika Nation, the Piikani Nation, the Kainai Nation, the Chiniki First Nation, the Bearspaw First Nation, the Goodstoney First Nation, and the Tsuut’ina First Nation at an Indigenous Celebration hockey game to honor the cultures of Indigenous peoples in Canada.

Former Secretary of State Deb Haaland leans out of a boat on a body of water. — In this 2022 photo, U.S. Secretary of the Interior Deb Haaland visits a wildlife refuge in Georgia. Haaland, a member of the Laguna Pueblo people, was the first Indigenous person to serve in this job.

Four men stand on a rocky beach working on traditional fishing equipment and nets. — Clayton Tuttle (right), J.J. Reed (left), and Jerry Brink (behind boulder) of the Karuk Tribe fish in the Klamath River in California.

© Katie Landeck/The Providence Journal—USA Today Network/Imagn Images, © Joseph Prezioso—AFP/Getty Images, © Gerry Thomas—NHLI/Getty Images, U.S. Department of the Interior, © Terray Sylvester—VWPics/Alamy

Did You Know?

Scientists haven’t been able to study most exoplanets closely because starlight makes it hard to see them. But the Nancy Grace Roman Space Telescope (currently being built, as seen in the photo) will be able to block starlight, giving us a clearer view of many more planets in our galaxy.

Sydney Rohde/NASA

A Recipe for Life

NASA/JPL-Caltech

This image shows the solar system of a star called Trappist-1. Scientists believe that some of these planets may be able to support life.

Do you believe there is life on other planets? Scientists are hopeful that there is. But a planet needs certain traits to support life.

It must be the right temperature. This means it can’t be too close or too far from its star.
It must be surrounded by a layer of gases called an atmosphere.
- Earth’s atmosphere contains a gas called oxygen, which most living things need to survive.
- Earth’s atmosphere also helps keep the air at the right temperature and protects living things from the Sun’s most harmful rays.
It must be a rocky planet, meaning its surface is solid instead of being made up of gases.
It must be within a certain size range. A very small planet does not have enough gravity to have an atmosphere. Very large planets have enough gravity to crush living things.

Scientists have identified a few exoplanets that may meet all of the above requirements. But they haven’t found signs of life—not yet, anyway!

A Powerful Telescope

NASA, ESA, CSA, STScI, Janice Lee (STScI), Thomas Williams (Oxford), and the PHANGS team

The James Webb Telescope captured this image of a spiral galaxy.

Scientists are studying the atmospheres of exoplanets with help from the James Webb Space Telescope. This giant telescope, which orbits the Sun, is more powerful than any telescope that came before.

You can learn more about the Webb telescope’s discoveries at Britannica!

Word of the Day

analysis

Part of speech:

noun

Definition:

: a careful study of something to learn about its parts, what they do, and how they are related to each other

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