The Solar System. The Inner Planets. The Solar System Overview Terrestrial Planets. Lecture 33. Chapter 16.1 16.8. The Big Bang – beginning of the Universe 12-16 billion years ago. Galaxies are flying away from each other No expansion within galaxies. Our Cosmic Origins.
12-16 billion years ago
Galaxies are flying away from each other
No expansion within galaxiesOur Cosmic Origins
Light year – distance which light travels in 1 year
From the Sun to Earth - 8 minutes
From the Sun to Pluto - 5 ½ hours
To the closest star - 4 years
Through the Milky Way - 100,000 years
To the closest galaxy - 2,500,000 yearsImages of Time
Size (diameter) - 1,392,500 kilometers (km)
Mass – 1.86 1030 kilograms (kg) or 98% of the total mass of the Solar system
Energy production rate – 4 million tons of mass (E=mc2)
Age – 4.6 billion years
Total stable life time - ~10 billion yearsThe Sun
Two families of planets in the Solar system: terrestrial (Earth-like) and Jovian (Jupiter-like)
The terrestrial planets are relatively small and almost spherical
The Earth has a radius of 6,378 km and an obliquity of 1/298
They are mostly made of rocky materials that can deform and flow
Every object exceeding ~500 km in diameter can become spherical under the influence of gravity
Planetary surfaces are all warmed by sunlight, but the high temperatures inside the planets today are due to radioactive heating.
The 2 smallest terrestrial worlds covered with lots of impact craters.
They have volcanic activity in the past (example - lunar maria).
Mercury has a 88-day orbit and a 59-day rotation.
Temperature is up to 425oC on the day side and down to 150oC on the night side.
It has many craters, but also traces of geological activity.
Venus is the third brightest object in the sky after the Sun and the Moon.
Venus has very similar parameters to those of the Earth.
However, it spins backwards (clockwise if looking from its north pole).
Its atmosphere has 96% CO2, surface temperature 400740 K, surface pressure is 90 times the Earth’s one.
It has volcanic activity, but probably no tectonic activity.
The Soviet spacecraft Venera 9 landed on Venus and send a panoramic view of its surface.
The US Magellan spacecraft transmitted radio images.
This is an intermediate-size planet and the most distant of the terrestrial planets from the Sun.
It has polar caps made of frozen CO2, many deserts, and volcanoes.
There is no liquid water on Mars today, but rather traces of past water flows.
The surface is different in the northern (low plains) and southern (highlands).
Only 13 missions to Mars out of 23 were successful.
Terrestrial planets are small and rocky
Only a handful geological processes shape the terrestrial planets
Every terrestrial world was heavily cratered long ago. Most of the craters are erased now.
Understanding of planetary geology might help us learn about planets of other star systems