Planet

PLANETS IN OUR SOLAR SYSTEM

The ancient Chinese named the five visible after their primary elements. Jupiter was the wood star, Mars the fire star , Saturn the earth star, Venus the metal star and Mercury the water star. Once they realized that the Earth was also a planet, they called it Diqiu, meaning "ball of earth."

The tradition of naming planets after mythological gods was passed down to us after Roman names for the five extraterrestrial planets they were aware of.

Venera 1 became the first man-made object to fly-by another planet by passing Venus on May 19, 1961. The Russian probe had lost contact with Earth a month earlier and did not send back any data.

Mockup (1:1) of the spacecraft Venera 1 at Memorial Museum of Astronautics (Moscow).

The Mariner 4 flyby of Mars took the first close-up photos of another planet on July 14, 1965.

Neptune and Uranus are not "Gas Giants" as is commonly believed, but belong to a separate category of giant planets called "Ice Giants." This is because less than 20% of their mass is made up of hydrogen and helium. True gas giants like Jupiter and Saturn are over 90% hydrogen and helium.

A "sysygy" occurs when all the planets of the our Solar System line up.

DWARF PLANETS

Eris, the largest known dwarf planet in the solar system, was discovered in January 2005 by the team of Michael E. Brown, Chad Trujillo, and David L. Rabinowitz using images originally taken on October 21, 2003, at the Palomar Observatory.

Eris (center) and Dysnomia (left of center), taken by the Hubble Space Telescope

The issue of a clear definition for planet came to a head in 2005 with the discovery of the trans-Neptunian object Eris, a body larger than the smallest then-accepted planet,

Mathematical calculations suggested that it was on July 11, 1735 that dwarf planet Pluto moved inside the orbit of Neptune for the last time before 1979.

On August 24, 2006 The International Astronomical Union redefined the term "planet" as a body that orbits the Sun, is massive enough for its own gravity to make it round, and has "cleared its neighbourhood" of smaller objects around its orbit. Under this new definition, Pluto, along with the other trans-Neptunian objects, does not qualify as a planet.

Pluto

The term dwarf planet was adopted in 2006 as part of a three-way categorization of bodies orbiting the Sun, brought about by an increase in discoveries of objects farther away from the Sun than Neptune that rivaled Pluto in size.

Eris is the most massive and second-largest known dwarf planet in the Solar System. It was discovered through image analysis on January 5, 2005 by a team of astronomers at the Palomar Observatory in California. In September 2006 it was named after the Greek goddess of strife and discord,

There is a dwarf planet, Sedna at the far outer reaches of the solar system which takes 10,000 Earth years to complete its journey around the sun.

EXO PLANETS

Radio astronomers Aleksander Wolszczan and Dale Frail announced on January 9, 1992 the discovery of two planets orbiting the pulsar PSR 1257+12, the first definitive detection of extrasolar planets.

The first confirmed discovery of an extrasolar planet orbiting a major star occurred on October 6, 1995, when Michel Mayor and Didier Queloz of the University of Geneva announced the detection of an exoplanet around 51 Pegasi.

Artist impression of the exoplanet 51 Pegasi. By ESO/M. Kornmesser/Nick Risinger (skysurvey.org)

Three independent observing campaigns announced in 2006 the discovery of OGLE-2005-BLG-390Lb through gravitational microlensing, the first cool rocky/icy extrasolar planet around a main-sequence star.

Kepler-186f is an exoplanet orbiting the red dwarf Kepler-186, 492 light-years from the Earth. It is the first planet with a radius similar to Earth's to be discovered in the habitable zone of another star. NASA's Kepler spacecraft detected it using the transit method, along with four additional planets orbiting much closer to the star. The results were presented initially at a conference on March 19, 2014. The public announcement was on April 17, 2014.

Artist's concept of a rocky Earth-sized exoplanet in the habitable zone of its host star, compatible with Kepler-186f’s known data 

Our Milky Way galaxy is home to the darkest planet ever discovered, TrES-2b, is a coal-black planet that reflects less than 1% of the starlight falling upon it.

There is a planet that is covered in burning ice. It is called Gliese 436 b. Its surface is at a constant 800ºF, but the ice remains as ice because the gravity of the planet is so incredibly powerful that it compresses all of the water vapor into a solid state. It is actually called ice-ten/ice X.

Astronomers discovered a bizarre rogue planet wandering the Milky Way. The free-range planet,  named SIMP J01365663+0933473, was first discovered back in 2016. It is nearly 13 times the mass of Jupiter and does not orbit a star, and also displays stunningly bright auroras that are generated by a magnetic field four million times stronger than Earth's.

There are an estimated 17 billion Earth-sized planets in the Milky Way, based on data from Nasa’s Kepler telescope.

Superhabitable planets is a recent definition/category of planets or moons that must meet much more criteria than just being in the "Habitable Zone/Goldilocks Zone". No planet or moon has met these criteria as of yet, although the planet Kepler-442b is the closest to this definition. A rocky near-Earth-sized exoplanet, it is 1206 light-years away from Earth and orbits within its star's habitable zone. 

Here is a list of songs with planets in the title.