The planets, stars and beyond. Nicola Loaring, SAAO.
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Nicola Loaring, SAAO
Whether or not they burn hydrogen in their cores. Stars do this; planets don't. In order to have high enough temperatures in the core to burn hydrogen, an object needs to have a mass of at least 75 or so times that of Jupiter. Anything more massive than that is automatically considered a star.
In giant molecular clouds
EUV imaging telescope image showing the Sun’s atmosphere at 60,000C.
This is hot, but the core is even hotter at ~15 million C!
Each granule is ~1000km across (CT to JoBurg!) and lasts 3-10 mins, like bubbles of boiling water.
Sunspot temperature ~3500C (cf ~5400C)
Venus is a similar size to the Earth, and is called our twin
It atmosphere is mainly Carbon dioxide and Nitrogen, with clouds of sulphuric acid!
Its very hot there due to the ‘Green house effect’ a whopping 462C
Earth is the 3rd planet from the Sun at a distance of 150 million km.
It has a diameter of 12,756 km only a few hundred km larger than that of Venus.
Our atmosphere is composed of 78 percent nitrogen, 21 percent oxygen and 1 percent other constituents.
71% of the Earth’s surface is covered by water!
Earth is the only planet in the solar system known to harbour life.
Picture taken by Apollo 17 astronauts
Orbits the Earth, completing one orbit every 29.5 days
Jupiter is the largest planet in the solar system – diameter is 11x the Earth’s diameter, mass is 318x the Earth’s mass.
Jupiter takes about 12 years to orbit the sun and is the fastest spinner in the solar system! Its day is about 10 hours.
Jupiter has faint rings and 63 moons.
Jupiter has the strongest magnetic field of all the planets, 14x that of the Earth.
Jupiter is famous for the Great Red Spot. This storm has been raging for ~350 years and is twice the size of Earth!
Neptune has the fastest winds in the solar system, over 2000km/hr!
Cloud tops are extremely cold at -218C
Pluto has been down-graded from a planet to a “dwarf planet”! In 2006 astronomers decided it didnt meet all 3 of the criteria for it to be defined as a planet.
1. Must orbit the Sun
2. Must be big enough that its own gravity squashes it into a round ball.
3.Must clear out other things from its orbit.