- Orion Arm (Wikipedia)
The Orion Arm is a minor spiral arm of the Milky Way Galaxy that is 3,500 light-years (1,100 parsecs) across and approximately 10,000 light-years (3,100 parsecs) in length, containing the Solar System, including Earth. It is also referred to by its full name, the Orion–Cygnus Arm (not to be confused with the outer end of the Norma Arm the Cygnus Arm), as well as Local Arm, Orion Bridge, and formerly, the Local Spur and Orion Spur.
- Solar System (Wikipedia)
The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. The largest of such objects are the eight planets, in order from the Sun: four terrestrial planets named Mercury, Venus, Earth and Mars, two gas giants named Jupiter and Saturn, and two ice giants named Uranus and Neptune. The terrestrial planets have a definite surface and are mostly made of rock and metal. The gas giants are mostly made of hydrogen and helium, while the ice giants are mostly made of ‘volatile’ substances such as water, ammonia, and methane. In some texts, these terrestrial and giant planets are called the inner Solar System and outer Solar System planets respectively.