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1d: Astronomy (Gravity (gravitational field strength decreases as you get…
1d: Astronomy
Gravity
If an object is traveling in a circle then there must be a force acting on it, as it is constantly changing direction.
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the planets move around the Sun in almost circular orbits. the forces that make this happen are provided by the gravity between each planet and the sun
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The Milky Way
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the distances between neighbouring stars is millions of times more than the distances between planets in our solar system.
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Types of Orbit
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Comets orbit the sun and have very elliptical orbits with the sun at one focus (near one end of the orbit)
Comets have orbital periods much longer than the earth, as they travel from the outer edges of the solar system. a comet travels much faster when its nearer the sun then it does in the more distant part because the increased pull of gravity makes it speed up the closer it gets to the sun.
Some artificial Earth satellites have an orbital period of exactly one day. they are called geostationary satellites, and are useful in communication because they're always over the same part of the planet,
Orbital speed
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For a circular orbit, the distance is the circumference of the orbit, which is given by the formula
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the universe is a large collection of billions of galaxies, which are even further apart than the stars
