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Here you can watch video lectures on astronomy topics. Watch one of 29 individual playlists, or use the Wikimap to find similar topics.

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Articles related to: Kuiper Belt  Read article

1. Oort Cloud  Read article

The comets we occasionally see as spectacular apparitions in the night sky are occasional visitors from the outer reaches of the solar system. In the 1950s the Dutch astronomer Jan Oort speculated about comets orbits and hypothesized the existence of a huge spherical cloud of comets spanning a dis...

2. Formation of Comets  Read article

Comets are icy planetesimals from the outer solar system. They were flung by close encounters with giant planets, primarily Jupiter, far away into the Oort cloud. Remember that even a tiny bit of Jupiter’s kinetic energy transferred by gravity to a tiny comet can fling it into deep space. NASA us...

3. Life Story of Comets  Read article

The life story of comets begins 4.6 billion years ago in the outer regions of the solar system as ice crystal and carbon rich dust grains aggregate into the nuclei of comets. Comets mostly exist beyond the orbit of Pluto and formed in the plane of the solar system. Many comets, however, were flung...

4. Comets  Read article

Comets are spectacular visitors to the inner solar system. They reach here on highly elliptical orbits from the outer reaches of the solar system far beyond the orbit of Pluto. A bright comet appears visible from the Earth without the benefit of binoculars about once per decade. The comets appear...

5. Orbits of Interplanetary Bodies  Read article

The different types of interplanetary bodies have different orbits. Asteroids are mostly found between the orbits of Mars and Jupiter, on nearly circular orbits; this is the region of the main asteroid belt. Most meteorites have orbits that are elliptical whose most distant point is somewhere in o...

6. Chaotic Orbits  Read article

Most orbits in the solar system are regular and repeatable. The orbits of the planets, for example, change very little over periods of hundreds of millions of years. Comet orbits, however, can be quite different. Comets are examples of solar system objects where the orbits can be chaotic. A chao...

7. Comets and Kepler's Laws  Read article

Comets travel on highly elliptical orbits. From Kepler's laws we know that the comet must travel faster when it's close to the Sun. Kepler's third law also relates the orbital period to the semi-major axis of the orbit. For Halley's Comet, with an orbital period of about 75 years, its most distan...

8. Life in the Solar System  Read article

The first place to conduct the search for life beyond Earth is our own solar system. Each of the planets in the solar system is hundreds of thousands of times closer than the next nearest extrasolar planets around nearby stars. So astronomers must start by closely inspecting all the planets and th...

9. Masses of Interplanetary Bodies  Read article

Interplanetary bodies can have spectacular effects on Earth, but they are a minor constituent of the solar system. The largest asteroid is Ceres, just over a thousand kilometers in diameter. That's twelve times smaller than the Earth and more than twice as small as Pluto. The next largest asteroi...

10. Comet Orbits  Read article

Comets have highly elliptical orbits around the Sun, and their activity depends on their distance from the Sun. At its most distant point, comets are usually far beyond the orbit of Pluto, and they're inactive. Their surfaces may be covered with dark dust from interplanetary space. As a comet spe...