Grade 4 · Science · 2 minutes
Our solar system
One star, eight planets, and a lot of empty space.
Key terms
- solar system
- The Sun and everything that travels around it, including the planets.
- orbit
- The path a planet follows around the Sun, held in place by gravity.
- asteroid belt
- A region between Mars and Jupiter with millions of space rocks.
- gas giant
- A huge planet made of gas, like Jupiter and Saturn.
- ice giant
- A cold, blue giant planet, like Uranus and Neptune.
- dwarf planet
- A small world, like Pluto, that shares its path with lots of other icy objects.
Transcript
Every star you see at night is a sun, far, far away. But one star is close enough to warm your face. It sits at the centre of our solar system.
The Sun is a giant ball of glowing gas, over a hundred times wider than Earth. Its gravity keeps the planets travelling around it, in paths called orbits.
Closest to the Sun are four rocky planets: Mercury, Venus, Earth and Mars. Then comes the asteroid belt, millions of space rocks between Mars and Jupiter.
Farther out are the giants. Jupiter and Saturn are huge balls of gas, and Jupiter is the biggest planet of all. Uranus and Neptune are ice giants, cold and blue.
And Pluto? In two thousand six, astronomers made it a dwarf planet. It's small, and it shares its path with lots of other icy objects.
Most pictures squeeze the planets together. But if the Sun were as tall as your front door, Earth would be about the size of a dime.
Now let's spread them out to their real distances. Sunlight reaches Earth in about eight minutes. Jupiter? Forty three minutes. Neptune? Over four hours. That's how empty space really is.
So remember: the Sun is a star at the centre. Gravity keeps eight planets in orbit, rocky ones inside, giants outside. And the space between them is enormous.
Sources
Every fact in the video, and where it comes from.
- 1science.nasa.gov/sun/facts
- The Sun is a star, a hot ball of glowing gas (mostly hydrogen and helium) at the centre of our solar system.
- The Sun's gravity holds the solar system together, keeping the planets in their orbits.
- 2science.nasa.gov/solar-system/planets
- The four inner planets (Mercury, Venus, Earth, Mars) are rocky (terrestrial).
- Jupiter and Saturn are gas giants; Uranus and Neptune are ice giants. Jupiter is the largest planet.
- 3science.nasa.gov/solar-system/asteroids/facts
- The main asteroid belt lies between the orbits of Mars and Jupiter and holds millions of asteroids.
- 4iau.org/public/themes/pluto
- In 2006 the IAU defined 'planet'; Pluto became a dwarf planet because it has not cleared the neighbourhood around its orbit (it shares it with Kuiper Belt objects).
- 5nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html
- Sun diameter about 1,391,000 km; Earth about 12,742 km: the Sun is about 109 times wider. If the Sun were a 2.03 m door, Earth would be about 18.6 mm across, close to a Canadian dime (18.03 mm), about 218 m away (1 AU = 107 solar diameters).
- 6en.wikipedia.org/wiki/Dime_(Canadian_coin)
- Sun diameter about 1,391,000 km; Earth about 12,742 km: the Sun is about 109 times wider. If the Sun were a 2.03 m door, Earth would be about 18.6 mm across, close to a Canadian dime (18.03 mm), about 218 m away (1 AU = 107 solar diameters).
- 7nssdc.gsfc.nasa.gov/planetary/factsheet
- Sunlight takes about 8.3 minutes to reach Earth, about 43 minutes to reach Jupiter (5.2 AU), and just over 4 hours (about 4 h 10 min, 30.1 AU) to reach Neptune. Mercury 3.2, Venus 6.0, Mars 12.7, Saturn 79, Uranus 160 min.
- 8universetoday.com/articles/how-long-does-it-take-sunlight-to-rea…
- Sunlight takes about 8.3 minutes to reach Earth, about 43 minutes to reach Jupiter (5.2 AU), and just over 4 hours (about 4 h 10 min, 30.1 AU) to reach Neptune. Mercury 3.2, Venus 6.0, Mars 12.7, Saturn 79, Uranus 160 min.
Image and sound credits
- Sun: NASA/SDO (AIA) (public domain), via Wikimedia Commons
- Mercury: NASA/Johns Hopkins University Applied Physics Laboratory/Arizona State (public domain), via Wikimedia Commons
- Venus: NASA/JPL-Caltech (public domain), via Wikimedia Commons
- Earth: NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron Evans (public domain), via Wikimedia Commons
- Mars: NASA / USGS (public domain), via Wikimedia Commons
- Jupiter: NASA, ESA, and A. Simon (Goddard Space Flight Center) (public domain), via Wikimedia Commons
- Saturn: NASA / JPL / Space Science Institute (public domain), via Wikimedia Commons
- Uranus: NASA/JPL-Caltech (public domain), via Wikimedia Commons
- Neptune: NASA / JPL / Voyager-ISS / Aster Cowart (public domain), via Wikimedia Commons
- Pluto: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Res (public domain), via Wikimedia Commons
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