The Milky Way is a spiral galaxy comprised of a bar-shaped core region surrounded by a flat disk of gas, dust and stars about 120,000 light-years wide. Our solar system is located about 27,000 light-years from the galactic center within one of the disk’s four spiral arms.

All in all, Hubble reveals an estimated 100 billion galaxies in the universe or so, but this number is likely to increase to about 200 billion as telescope technology in space improves, Livio told Space.com.

But only in the past few decades have we come to understand that the Milky Way is one of the 100 billion galaxies in the universe, and that its disk stretches some 100,000 light-years across. For decades, astronomers believed the Milky Way was a simple spiral galaxy.

Astronomers have discovered a vast assemblage of galaxies hidden behind our own, in the “zone of avoidance.” The starry core of our spiral Milky Way galaxy, in an infrared image from NASA Spitzer Space Telescope.

An extragalactic planet, also known as an extragalactic exoplanet, is a star-bound planet or rogue planet located outside of the Milky Way Galaxy. Due to the huge distances to such worlds, they would be very hard to detect directly. However, indirect evidence suggests that such planets exist.

Planets in Our Solar System

• Mercury. Mercury—the smallest planet in our solar system and closest to the Sun—is only slightly larger than Earth’s Moon.
• Venus. Venus spins slowly in the opposite direction from most planets.
• Earth.
• Mars.
• Jupiter.
• Saturn.
• Uranus.
• Neptune.

Order Of the Planets From The Sun

• Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. An easy mnemonic for remembering the order is “My Very Educated Mother Just Served Us Noodles.”
• Mercury:
• Venus:
• Earth:
• Mars:
• Jupiter:
• Saturn:
• Uranus:

According to the International Astronomical Union, the organization charged with naming all celestial bodies and deciding on their statuses, Pluto is still not an official planet in our solar system. Pluto was found to be smaller and less massive than all the other planets.

dwarf planet