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What IS a Satellite?

May 20, 2016

The first man-made satellite didn't come along until 1957. Today, thousands of artificial satellites orbit Earth, with many others orbiting the sun and planets.


Image of a satellite in space

At NOAA’s Satellite and Information Service, we talk an awful lot about "satellites"... for obvious reasons. But did you know the word satellite actually refers to any object (man-made or natural) orbiting another, larger object?

For example, the moon is actually a satellite orbiting Earth. Even Earth can be considered a satellite because it orbits the sun! Generally speaking, however, the term “natural satellite” is usually reserved for moons and other celestial objects that orbit planets, dwarf planets, and minor planets.

Image of the earth and moon
On July 16, 2015, NASA’s EPIC camera, aboard NOAA’s DSCOVR satellite, captured this unique view of Earth’s very own satellite—the moon. Taken from one million miles away, this image shows the moon moving over the Pacific Ocean near North America. The North Pole is in the upper left corner of the image, reflecting the orbital tilt of Earth from the vantage point of the spacecraft. Credit NASA/NOAA

The first man-made satellite didn't come along until 1957, when the Soviet Union successfully placed Sputnik-1 in orbit around Earth.Today, thousands of artificial satellites orbit Earth, with many others orbiting the sun and planets.

Earth-orbiting satellites range from weather and communications satellites, to deep space telescopes and U.S. Global Positioning System (GPS) satellites. There are even satellites that orbit Earth one million miles away. As of 2016, over 50 countries and several multinational organizations are involved in building, launching, and/or operating a satellite.

Weather and environmental observing satellites, like the ones operated here at NOAA, usually consist of three main sections: the bus (the body of the satellite), the instruments (the sensors, imagers, and sounders that collect and send data back to Earth) and the power source (comprised of batteries and/or solar array panels). These satellites measure a growing array of variables that help agencies like NOAA’s National Weather Service create daily forecasts and predict and monitor dangerous weather events. They also contribute to long-term data sets that help scientists, educators, and members of the public understand and monitor our dynamic and changing planet.

Image of all the satellites orbiting the earth

While NOAA operates many satellites, no one country alone can afford to effectively monitor the entire planet. NOAA partners with the international community to leverage data from satellites around the world, providing a more complete understanding of our ever changing planet. This image shows the current space-based portion of the World Meteorological Organization's Global Observing System, plus additional space weather and environmental satellites. Credit: NOAA

NOAA currently operates satellites in polar orbit, geostationary orbit and one satellite in deep space at Lagrange point 1. Polar-orbiting satellites circle Earth from pole to pole and provide global information from 540 miles above the surface. NOAA's geostationary satellites orbit at speeds equal to Earth's rotation, allowing them to constantly monitor the western hemisphere from 22,240 miles above the planet's surface. NOAA's deep-space satellite, DSCOVR , orbits 1 million miles from Earth, a gravity-neutral point in space, where it can remain between the sun and the sun-lit side of Earth at all times.

Need more space? Learn more about NOAA’s satellite missions!

Satellite Fun Facts

  • Explorer 1 was the first U.S. satellite successfully placed in orbit and the first satellite to carry scientific instruments into space.
  • The first meteorological experiment made it to space aboard the Explorer-7 satellite in 1959.
  • The first dedicated meteorological satellite in orbit was TIROS-1, launched in 1960.
  • The International Space Station is the largest man-made satellite currently in orbit.
  • The Solar System has approximately 182 known natural satellites.
  • NOAA’s first operational geostationary satellite, GOES-1, launched on October 16, 1975.
  • The seven largest natural satellites in the Solar System (those bigger than 2,500 km across) are Jupiter's Galilean moons (Ganymede, Callisto, Io, and Europa), Saturn's moon Titan, Earth's moon, and Neptune's captured natural satellite Triton.
  • NOAA's DSCOVR satellite is the United States’ first operational deep space satellite.
  • NOAA currently operates 15 operational environmental and meteorological satellites around Earth.
  • The first artificial Earth satellite powered by solar cells was Vanguard-1, launched March 17, 1958.
  • Vanguard-1 is the oldest man-made satellite still in orbit, having orbited Earth for 58 years, and is expected to continue to do so for nearly another two centuries.
  • In 2013, NASA’s LandSat 5 set the Guinness World Record for “Longest Operating Earth Observation Satellite” after operating for 28 years and 10 months.

Have your own satellite fun fact or satellite related question? Send them to us @NOAASatellites!