Astronomy

GALAXY FACTS
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust. Examples of galaxies range from dwarfs with as few as ten million stars to giants with a hundred trillion stars, each orbiting their galaxy’s own center of mass. There are probably more than 170 billion galaxies in the observable universe.

Gigapixels of Andromeda
The Andromeda Galaxy
Hubble Space Telescope & the Formation of the Galaxy

The Solar System

1. A solar system refers to a star and all the objects that travel in orbit around it. Our solar system consists of the sun - our star - eight planets and their natural satellites (such as our moon); dwarf planets; asteroids and comets. Our solar system is located in an outward spiral of the Milky Way galaxy.

3D Solar System Simulator

1. Soho
2. Sun

   Star
3. The Sun is the star at the center of the Solar System. It is by far the most important source of energy for life on Earth. Wikipedia
5. Distance to Earth: 149,600,000 km
6. Surface temperature: 5,778 K
7. Mass: 1.989E30 kg
8. Magnitude: -26.74
9. Radius: 695,800 km (1 R☉)
10. Orbits: Galactic Center

The Sun

1. Mercury

   Planet
2. Mercury is the smallest and closest to the Sun of the eight planets in the Solar System, with an orbital period of about 88 Earth days. Wikipedia
4. Radius: 2,440 km
5. Surface area: 74,800,000 km²
6. Mass: 328.5E21 kg (0.055 Earth mass)
7. Distance from Sun: 57,910,000 km
8. Orbital period: 88 days
9. Length of day: 58d 15h 30m

1. Venus

   Planet
2. Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has no natural satellite. It is named after the Roman goddess of love and beauty. Wikipedia
4. Surface area: 460,234,317 km²
5. Radius: 6,052 km
6. Length of day: 116d 18h 0m
7. Mass: 4.867E24 kg (0.815 Earth mass)
8. Distance from Sun: 108,200,000 km
9. Orbital period: 225 days

1. Earth

   Planet
2. Earth, also called the world and, less frequently, Terra or Gaia, is the third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets, ... Wikipedia
4. Age: 4.54 billion years
5. Radius: 6,371 km
6. Distance from Sun: 149,500,000 km
7. Mass: 5.972E24 kg
8. Population: 7.125 billion (2013) World Bank
9. Moon: Moon

The story of Earth ~ NGC 

1. Mars

   Planet
2. Mars is the fourth planet from the Sun and the second smallest planet in the Solar System, after Mercury. Wikipedia
4. Gravity: 3.711 m/s²
5. Radius: 3,390 km
6. Mass: 639E21 kg (0.107 Earth mass)
7. Surface area: 144,798,500 km²
8. Length of day: 1d 0h 40m
9. Moons: Phobos, Deimos

1. Jupiter

   Planet
2. Jupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a gas giant with mass one-thousandth of that of the Sun but is two and a half times the mass of all the other planets in the Solar System combined. Wikipedia
4. Radius: 69,911 km
5. Surface area: 61,418,738,571 km²
6. Mass: 1.898E27 kg (317.8 Earth mass)
7. Gravity: 24.79 m/s²
8. Distance from Sun: 778,500,000 km
9. Moons: Europa, Io, Ganymede, Callisto, Amalthea, Metis, Adrastea,more

1. Saturn

   Planet
2. Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Named after the Roman god of agriculture, its astronomical symbol represents the god's sickle.Wikipedia
4. Radius: 58,232 km
5. Surface area: 42,700,000,000 km²
6. Mass: 568.3E24 kg (95.16 Earth mass)
7. Distance from Sun: 1,433,000,000 km
8. Orbital period: 29 years
9. Moons: Titan, Enceladus, Mimas, Rhea, Dione, Iapetus, Tethys, more

1. Neptune

   Planet
2. Neptune is the eighth and farthest planet from the Sun in the Solar System. It is the fourth-largest planet by diameter and the third-largest by mass. Among the gaseous planets in the Solar System, Neptune is the most dense. Wikipedia
4. Radius: 24,622 km
5. Surface area: 7,618,272,763 km²
6. Mass: 102.4E24 kg (17.15 Earth mass)
7. Orbital period: 165 years
8. Distance from Sun: 4,503,000,000 km
9. Moons: Triton, Nereid, Naiad, Proteus, Larissa, Galatea, Despina,Thalassa, Neso, Psamathe, Sao, Laomedeia, Halimede

1. Uranus

   Planet
2. Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System.Wikipedia
4. Radius: 25,362 km
5. Surface area: 8,083,079,690 km²
6. Mass: 86.81E24 kg (14.54 Earth mass)
7. Distance from Sun: 2,877,000,000 km
8. Orbital period: 84 years
9. Moons: Miranda, Titania, Umbriel, Oberon, Ariel, Puck, Cordelia, more

1. Pluto 
   
   (134340 Pluto) is the largest object in the Kuiper belt, [i] [j] the tenth-most-massive known body directly orbiting the Sun; and the second-most-massive known dwarf planet, after Eris.
   
   Radius: 1,184 km
   Discovered: February 18, 1930
   Gravity: 0.658 m/s²
   Orbits: Sun
   Discoverer: Clyde Tombaugh
   Moons: Charon, Styx, Hydra, Nix, Kerberos

New Horizons arrives on July 14, 2015
NASA's New Horizons Mission Continuing Voyager's Legacy of Exploration


NASA
Astrophysics UC Berkeley 1~ 25

TV Series
Cosmos~Carl Sagan

Space