Satellites Artificial Satellites are man made objects that
Satellites Artificial Satellites are man -made objects that are launched in to space and orbit Earth They are held in orbit by Earth’s gravity and their own velocity Over time their orbit will decay and they can fall back to Earth This shows all the satellites and space debris in low Earth orbit
Gravity and satellites A satellite is any object that orbits another object. The Moon is a natural satellite of the Earth and is kept in orbit by the attraction of the Earth’s gravity. An artificial satellite is an object made by and put into orbit by humans. There are lots of artificial satellites in orbit around the Earth and they have many different uses. Artificial satellites can have different type of orbits. 1 20 2 of 27 © Boardworks Ltd 2006 2004
Geostationary satellites: l Stay above the same geostationary point on Earth. orbit l Speed of orbit matches the Earth’s rotation, so orbit time is 24 hours. l Used for communications, satellite TV, weather forecasting, intelligence, global positioning systems (GPS). 1 20 3 of 27 © Boardworks Ltd 2006 2004
Polar orbit satellites: polar orbit l Low orbit around the Earth passing over North and South poles. l Earth rotates underneath them as they orbit. l Used for large-scale mapping and global weather monitoring. 1 20 4 of 27 © Boardworks Ltd 2006 2004
Uses for Satellites have many uses including: Communications Global Positioning System Predicting Weather Scientific surveys of the Earth's surface • Map making • Spying • TV • • Satellites use solar panels as a renewable way to power their systems
Using satellites to view space Astronomical satellites, such as the Hubble Space Telescope (HST), are large telescopes placed in a high orbit far from the effects of the Earth’s atmosphere. These satellites can ‘see’ much further into space and give us images of stars and galaxies many light years away, like this cartwheel galaxy. 1 20 6 of 27 © Boardworks Ltd 2006 2004
Repairing satellites Meteorites, the Solar Wind and ‘space junk’ all travel very quickly through space and can damage satellites. Astronauts need to ‘space-walk’ in order to fix them. 1 20 7 of 27 © Boardworks Ltd 2006 2004
Space Telescopes A telescope in space has no light pollution or interference from the atmosphere They are incredibly expensive though The Hubble Space Telescope was launched in 1994 When the Hubble was first launched it didn’t work It needed ‘spectacles’ due to a mistake
Space Probes Space probes are used to explore our solar system and beyond Because they are unmanned they can be made quite small and they don’t need to carry food or oxygen This makes them a lot cheaper than manned space flights Voyager 1 was launched in 1977 and is very close to entering interstellar space Every year it travels the same distance as there is between the Earth and Sun
Which type of satellite? 1 10 ofof 20 27 © Boardworks Ltd 2006 2004
Questions about satellites 1. Give two uses of artificial satellites. 2. What is meant by a ‘geostationary’ orbit? 3. What problems do satellites encounter in space? 4. Why can the Hubble Space Telescope ‘see’ much further into space and produce much clearer images than telescopes on Earth? 5. Why do astronauts have to wear ‘space suits’ when repairing satellites? 1 11 ofof 20 27 © Boardworks Ltd 2006 2004
Eclipses A solar eclipse happens when the Moon passes between the Sun and the Earth. This casts a shadow over the Earth A lunar eclipse happens when the Earth passes between the Sun and the Moon. This casts a shadow over the Moon. Solar eclipses are very rare however lunar eclipses happen most years
Eclipses Solar Eclipse Lunar Eclipse
- Slides: 14