* 1989 – Voyager 2 spacecraft makes its closest approach to Neptune, the second to last planet in the Solar System at the time.

What makes an individual substance – a man, a tree, a planet – real is a distinct act, a " to be ", which actuates its unity.

The hydrogen and helium in " traditional " gas giants like Jupiter and Saturn constitutes most of the planet, whereas the hydrogen / helium only makes up an outer envelope on Uranus and Neptune which are sometimes called ice giants, as they are mostly composed of water, ammonia, and methane molten ices.

The metallic hydrogen layer makes up the bulk of each planet, and is described as " metallic " because the great pressure turns hydrogen into an electrical conductor.

* Desolation Road ( 1988 ) by Ian McDonald is a magic-realist science fiction novel set on a planet that's never explicitly named ( though the name " Ares " makes frequent appearances in various contexts ) but is clearly meant to be a terraformed Mars.

This makes it the tallest mountain on any planet in the Solar System ( and, after the 2011 discovery of Rheasilvia Mons on 4 Vesta, the second largest mountain on any world known to man ).

First, it is very difficult to conceive of a world wherein every man, woman, and child grew up in the same environment, because their spatial and temporal dispersion upon the planet Earth makes it impossible.

Much later, once more in possession of the Power Gem, the Champion had settled on the planet Skardon, whose native Skard exist in a " might makes right " culture ; all disputes, including matters of law, are settled in a trial by combat, with the winner of the fight thus becoming the winner of the dispute.

In Star Trek: First Contact, it is stated that but for Zefram Cochrane's historic warp flight, a passing Vulcan ship would have deemed Earth unready for contact and ignored the planet, and in the Enterprise episode " Fight or Flight " T ' Pol makes reference to a Vulcan policy of non-interference.

In " The Paradise Syndrome "," the Enterprise attempts to save a pre-industrial planet by moving an asteroid that was on a collision course with it ; when McCoy asks Kirk if he should warn the people, Kirk and Spock only point out the people would not understand the warning, and neither makes any reference to the Prime Directive.

To avoid a war with the Chiss, Leia suggests to " UnuThul " ( as Raynar was now known ) that the Killik nest be moved to a new planet, but makes him think it is his idea.

* Gong album 2032 ( released September 2009 ) describes the year 2032 to be the year that the Planet Gong makes full contact with the planet Earth

After Trevize makes his decision, the intellect of Gaia adjusts Branno's mind so that she believes she has become victorious and conquered the planet ( but that she will also continue to leave it alone ) and Gendibal is sent back to the Second Foundation under the impression that the Second Foundation is victorious and should continue as normal.

Discovering that this leaves behind a small child who will be put to death if left alone, Bliss makes the decision to keep the child as they quickly escape the planet.

The wisdom planet in the house of speech makes one scholarly.

The linear momentum gained by the spaceship is equal in magnitude to that lost by the planet, though the planet's enormous mass compared to the spacecraft makes the resulting change in its speed negligibly small.

But he is shocked into personally surrendering to Jedrik after the God Wall Caleban makes the sky of Dosadi black in preparation for the destruction of the planet.

This makes interpretation of periodicities in the radial velocity of Epsilon Eridani, such as those caused by the gravitational perturbations of an orbiting planet, more difficult.

Mantrid makes an appearance in the third season as well, resurrected on the desolate planet Fire to suffer punishment for his choices.

* December 14 – 23 – The Voyager, piloted by Dick Rutan and Jeana Yeager, makes the first non-stop flight around the planet without refueling.

* The concept of horizontality only makes sense in the context of a clearly measurable gravity field, i. e., in the ' neighborhood ' of a planet, star, etc.

Our destination is planet Deneb IV ..." Writers and producers have selected numbers using different methods over the years, some more arbitrary than others, which makes it impossible to convert all stardates into equivalent calendar dates.

The Imperial planet of Sparta occupies a system containing an orange dwarf K0 primary with a red dwarf companion ( described in The Gripping Hand ) which makes passes close enough to impact Sparta's climate.

The possession of a single lordship of at least a single inhabited planet in a stellar system populated by less than one hundred million inhabitants automatically makes that domain a county.

The Brahmaputra has its headwaters in the tableland of the world, the towering white headwalls of the Himalayas that are unknown to man as any other space on the planet.

and, now and in the future unlike in the past, any attempt to repel injury and to preserve any particular civilized attainment of mankind or its provisional justice runs some risk of nuclear warfare and the danger that an effect of it will, by human action, render this planet less habitable by the human race.

In Asimov's Empire and Foundation series, the capital planet Trantor of the galactic empire is a completely built-up planet, covered in its entirety with tall buildings and subterranean structures.

Aberration should also be distinguished from light-time correction, which is due to the motion of the observed object, like a planet, through space during the time taken by its light to reach an observer on Earth.

For the case of an object that is small compared with the radial distance to its axis of rotation, such as a tin can swinging from a long string or a planet orbiting in a circle around the Sun, the angular momentum can be expressed as its linear momentum,, crossed by its position from the origin, r. Thus, the angular momentum L of a particle with respect to some point of origin is

In orbits, the angular momentum is distributed between the spin of the planet itself and the angular momentum of its orbit:

If a planet is found to rotate slower than expected, then astronomers suspect that the planet is accompanied by a satellite, because the total angular momentum is shared between the planet and its satellite in order to be conserved.

* The planet Uranus is colored cyan because of the abundance of methane in its atmosphere.

The Blue Planetary was discovered by John Herschel and named for its color's similarity to Uranus, though the nebula is three times larger than the planet.

Brian Marsden of the Central Bureau for Astronomical Telegrams noted that the comet lay only about 4 degrees from Jupiter as seen from Earth, and that while this could of course be a line of sight effect, its apparent motion in the sky suggested that it was physically close to the giant planet.

A search of historical observations revealed that the spots were probably the most prominent transient features ever seen on the planet, and that while the Great Red Spot is notable for its striking color, no spots of the size and darkness of those caused by the SL9 impacts have ever been recorded before.

The entire species dies out every 50, 000 years except for one who tends for all the eggs, which take the form of silicon nodules scattered throughout the caverns and tunnels of its home planet, Janus VI.

* in Doctor Who's first series after its revival, episodes 4-5 and 11 featured the alien Slitheen family of the planet Raxicoricofallapatorius, which were said to be Calcium-based life forms, causing them to be blown up in contact with vinegar.

In the Halo franchise, the weak, low-ranking Grunts of the Covenant originate on a frozen exoplanet named Balaho, where methane is a primary constituent of the atmosphere, prevents the planet becoming even more frigid than it already is due to its distance from its parent star, and thus, Grunts have evolved to utilize the gas for respiration.

In the special case of a planet in circular orbit around its star, for example, where is zero, the centripetal acceleration alone is the entire acceleration of the planet, curving its path toward the sun under the force of gravity, the negative F ( r ).

The radio emission of a planet was first detected in 1955, when Burke and Franklin ( 1955 ) identified the origin of interference-like radio noise on their records at about 15 meters wave length as emission from Jupiter.

The Seventh-day Adventist Church, teaches that the first death, or death brought about by living on a planet with sinful conditions ( sickness, old age, accident, etc.

It will later become the first spacecraft to successfully transmit data from the surface of another planet ( Venus ).

Although he is best known for discovering the dwarf planet Pluto in 1930, the first object to be discovered in what would later be identified as the Kuiper belt, Tombaugh also discovered many asteroids ; he also called for serious scientific research of unidentified flying objects.

It was the first comet observed to be orbiting a planet, and had probably been captured by the planet around 20 – 30 years earlier.

HST images of a fireball from the first impact appearing over the limb of the planet

One of the first proposed estimates of the total number of beetle species on the planet is based on field data rather than on catalog numbers.

It is the first successful soft landing on another planet

* 1612 – Galileo Galilei becomes the first astronomer to observe the planet Neptune, although he mistakenly catalogued it as a fixed star.

In 1976 he earned acclaim for his first major film role, portraying Thomas Jerome Newton, an alien from a dying planet, in The Man Who Fell to Earth, directed by Nic Roeg.

When he first encounters the Fourth Doctor in Genesis of the Daleks, Davros is the chief scientist of the Kaleds, one of two native sentient races of the planet Skaro.

The first confirmed detection of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi.

Kepler-16 contains the first discovered planet that orbits around a binary star system.

The first confirmed discovery of an extrasolar planet was made using this method.

The first planet discovered in a system is given the designation " b " and later planets are given subsequent letters.

For instance, in the 55 Cancri system the first planet – 55 Cancri b – was discovered in 1996 ; two additional farther planets were simultaneously discovered in 2002 with the nearest to the star being named 55 Cancri c and the other 55 Cancri d ; a fourth planet was claimed ( its existence was later disputed ) in 2004 and named 55 Cancri e despite lying closer to the star than 55 Cancri b ; and the most recently discovered planet, in 2007, was named 55 Cancri f despite lying between 55 Cancri c and 55 Cancri d. As of April 2012 the highest letter in use is " j ", for the unconfirmed planet HD 10180 j ( HD 10180 h is the confirmed planet with the highest letter ).

However, the " A " is sometimes omitted ; for example the first planet discovered around the primary star of the Tau Boötis binary system is usually called simply Tau Boötis b.

During the first decade of the television series, the name of the Doctor's home planet was not revealed, although it was actually shown for the first time in The War Games ( 1969 ) during the Doctor's trial.