How can artificial satellites be used

Since then, dozens of countries have launched satellites, with more than 3, currently operating spacecraft going around the Earth. There are estimated to be more than 8, pieces of space junk; dead satellites or pieces of debris going around the Earth as well. Satellites are launched into different orbits depending on their mission. One of the most common ones is geosynchronous orbit.

This is where a satellite takes 24 hours to orbit the Earth; the same amount of time it takes the Earth to rotate once on its axis. As of late , Jupiter has 69 known moons, Saturn has 53, Uranus has 27 and Neptune has 13 or New moons are occasionally discovered — mainly by missions either past or present, as we can analyze old pictures or by performing fresh observations by telescope.

Saturn is a special example because it is surrounded by thousands of small objects that form a ring visible even in small telescopes from Earth. Scientists watching the rings close-up over 13 years, during the Cassini mission , saw conditions in which new moons might be born.

Scientists were particularly interested in propellers, which are wakes in the rings created by fragments in the rings. Just after Cassini's mission ended in , NASA said it's possible the propellers share elements of planet formation that takes place around young stars' gassy discs. Even smaller objects have moons, however.

Pluto is technically a dwarf planet. However, the people behind the New Horizons mission , which flew by Pluto in , argue its diverse geography makes it more planet-like. One thing that isn't argued, however, is the number of moons around Pluto. Pluto has five known moons, most of which were discovered when New Horizons was in development or en route to the dwarf planet. A lot of asteroids have moons, too. These small worlds sometimes fly close to the Earth, and the moons pop out in observations with radar.

There are also examples of asteroids with rings , such as Chariklo and Chiron. Many planets and worlds in our solar system have human-made "moons" as well, particularly around Mars — where several probes orbit the planet doing observations of its surface and environment. The planets Mercury, Venus, Mars, Jupiter and Saturn all had artificial satellites observing them at some point in history. Technically speaking, during the Apollo missions, humans flew in artificial "moons" spacecraft around our own moon between and NASA may even build a " Deep Space Gateway " space station near the moon in the coming decades, as a launching point for human Mars missions.

Fans of the movie "Avatar" will remember that the humans visited Pandora, the habitable moon of a gas giant named Polyphemus. We don't know yet if there are moons for exoplanets, but we suspect — given that the solar system planets have so many moons — that exoplanets have moons as well. In , scientists made an observation of an object that could be interpreted as an exomoon circling an exoplanet , but the observation can't be repeated as it took place as the object moved in front of a star.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community space. Elizabeth Howell is a contributing writer for Space. Access through your institution. Buy or subscribe. Rent or Buy article Get time limited or full article access on ReadCube. References 1 King-Hele, D. View author publications. Rights and permissions Reprints and Permissions. Copy to clipboard. Comments By submitting a comment you agree to abide by our Terms and Community Guidelines.

Search Search articles by subject, keyword or author. Related content Read about natural satellites , communications satellites and learn about how satellites are launched into space and how some of them have become space junk.

Activity ideas Get your students turn their eyes to the night sky to observe natural satellites and to spot artificial satellites — like the ISS — as they pass overhead. Useful links High resolution imagery from the Geoeye-1 satellite. Go to full glossary Add 0 items to collection. Download 0 items. Twitter Pinterest Facebook Instagram. Email Us. See our newsletters here. Would you like to take a short survey?

This survey will open in a new tab and you can fill it out after your visit to the site. Yes No.