The term most commonly applies to a spacewalk made outside a craft orbiting Earth ( such as the International Space Station ), but also has applied to lunar surface exploration ( commonly known as moonwalks ) performed by six pairs of American astronauts in the Apollo program from 1969 to 1972.

The spacecraft discovered Ida has a moon Dactyl, the first discovery of a natural satellite orbiting an asteroid.

A satellite orbiting the Earth has a tangential velocity and an inward acceleration.

A planet () is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.

< span style =" font-size: 90 %;"> ( Red Faction )</ span ></ ref > After sending a distress call to the Earth Defense Force Parker destroys the missile defense system, so that he can stow away on a shuttle to an Ultor space station in Martian orbit to deactivate a laser defense system without getting shot down .< ref > Hendrix: Ultor has a system of laser satellites orbiting Mars.

For example, X-ray astronomy is nearly impossible when done from the Earth, and has reached its current importance in astronomy only due to orbiting X-ray telescopes such as the Chandra observatory and the XMM-Newton observatory.

Recent measurements of its motion indicate that it is moving at per second in the direction of the Andromeda Galaxy, which has led astronomers to surmise that it may actually be orbiting the larger galaxy.

In 2004, a team of UK astronomers led by Jane Greaves discovered that Tau Ceti has more than ten times the amount of cometary and asteroidal material orbiting it than does the Sun.

One solution to these paradoxes is the Charlier universe, in which the matter is arranged hierarchically ( systems of orbiting bodies that are themselves orbiting in a larger system, ad infinitum ) in a fractal way such that the universe has a negligibly small overall density ; such a cosmological model had also been proposed earlier in 1761 by Johann Heinrich Lambert.

* March 5 – NASA announces that the Clementine probe orbiting the Moon has found enough water in polar craters to support a human colony and rocket fueling station.

A synchronous orbit is an orbit in which an orbiting body ( usually a satellite ) has a period equal to the average rotational period of the body being orbited ( usually a planet ), and in the same direction of rotation as that body.

Kawasaki has also participated in projects such as the development of reusable launch vehicles for spacecraft that will handle future space transport, space robotics projects such as the Japanese Experiment Module for the International Space Station, the HOPE-X experimental orbiting plane and the docking mechanism for the ETS-VII.

Despite this, it has been suggested that radio pulses recorded by the spacecraft Venus Express ( which began orbiting Venus in April 2006 ) may originate from lightning on Venus.

* Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth ; for example, because the star has an orbiting companion that sometimes eclipses it.

Cygnus X-1 has since been studied extensively using observations by orbiting and ground-based instruments.

With an angular resolution of 0. 5 arcsecond ( 2. 4 µrad ), it has a thousand times better resolution tnan the first orbiting X-ray telescopes.

In the main part of the series, the frontier has moved away from Venus after explorers discovered an asteroid orbiting perpendicular to the ecliptic plane, filled with cobalt blue tunnels, and hundreds of small Heechee spaceships.

In an alternative scenario, the exozodiacal dust may be generated in an outer belt, which is orbiting between 55 and 90 AU from the host star and has an assumed mass of 10 < sup >− 3 </ sup > times the mass of the Earth.

A satellite orbiting the earth has a Speed # Tangential Speed | tangential velocity and an inward acceleration.

The invention of engines that can surpass the speed of light has made it possible for the colony to explore far and wide ; the second part finds them studying a planet orbiting the star Praesepe over 500 light years away.

It has not been identified as a member of a specific stellar moving group and is orbiting through the Milky Way galaxy at a distance from the core that varies from with an orbital eccentricity of 0. 052.

On multiple occasions this star has been examined for the existence of a low stellar mass or brown dwarf companion orbiting at a distance of at least 1 astronomical unit from the primary.

Spectroscopic analysis of HD 209458 b, an extrasolar planet in this constellation has provided the first evidence of atmospheric water vapor beyond the solar system, while extrasolar planets orbiting the star HR 8799 also in Pegasus are the first to be directly imaged.

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

The planet is probably very similar to the other " hot Jupiters " orbiting nearby stars.

He replies that the aliens would probably send a scout to test the humans ' defenses, and when one of the orbiting ships breaks formation and enters the atmosphere, the military demands a show of force.

Notably, at the time of its announcement in January 2006, the planet OGLE-2005-BLG-390Lb probably had the lowest mass of any known exoplanet orbiting a regular star, with a median at 5. 5 times the mass of the Earth and roughly a factor two uncertainty.

He waited until 1802 ( in Catalogue of 500 new Nebulae, nebulous Stars, planetary Nebulae, and Clusters of Stars ; with Remarks on the Construction of the Heavens ) to announce the hypothesis that the two stars might be " binary sidereal systems " orbiting under mutual gravitational attraction, a hypothesis he confirmed in 1803 in his Account of the Changes that have happened, during the last Twenty-five Years, in the relative Situation of Double-stars ; with an Investigation of the Cause to which they are owing.

( When orbiting the earth, the last two terms are known as the apogee and perigee.

This means that the stream of particles that produces this shower is narrow – and apparently deriving from and within the last 500 years from some orbiting body.

The third launch succeeded in orbiting three satellites, and the fourth and last qualification launch was also a success.

They agreed to open up the surrounding four dams, but after unlocking the last one, they are captured and sentenced to death upon the Gaira satellite ; it begins orbiting to Palm, and, once in contact, both the satellite and the planet are completely destroyed.

In his dream, Londo recalls the threat he gave to G ' Kar last year (" Keep this up G ' Kar, and soon you won't have a planet to protect ") followed by the image of the destruction of the Centauri starbase orbiting Ragesh 3.

Back-tracing its orbit showed that the object had been orbiting the Sun for 31 years and had last been in the vicinity of the Earth in 1971.

The Doctor manifests in the Solar system, aboard an immense Federation space station orbiting Jupiter, where Zimmerman has spent the last four years developing new holographic technology.

But in order to gain access to Sirius, Sam is asked to storm Kronor, a moon orbiting Sirius that has a massive cannon which could be used to remove Sirius ' protection shield, which was a last line of defense for the Sirians against Mental.

As the series presents it, known human contact with the Chigs begins when an unmanned probe, launched by the military-industrial corporation Aerotech, lands on a celestial body designated " celestial body 2064K " ( later given military designation ' Anvil '), the single moon orbiting the Chig homeworld.

is the provisional designation of an object seen orbiting Saturn just beyond the outer strand of the F ring on June 21, 2004.

is the provisional designation of a dusty object seen orbiting Saturn very close to the F ring.

if a substantial fraction of the dust is orbiting about the Earth, only about one third the above-mentioned average velocity should be used in deriving the mass.

She was the sun, he the closest planet orbiting around her, the rest of the world existing and visible yet removed.

Now as you step inside, instead of seeing particles orbiting around like planets, you see waves and ripples very much like the ripples that you get on the surface of a pond when you drop a stone into it.

These terms have historically been applied to any astronomical object orbiting the Sun that did not show the disk of a planet and was not observed to have the characteristics of an active comet, but as small objects in the outer Solar System were discovered, their volatile-based surfaces were found to more closely resemble comets, and so were often distinguished from traditional asteroids.

NASA's planned Space Interferometry Mission ( SIM PlanetQuest ) ( now cancelled ) was to utilize astrometric techniques to detect terrestrial planets orbiting 200 or so of the nearest solar-type stars, and the European Space Agency's GAIA ( due to launch in 2012 ), which will be applying astrometric techniques in its stellar census.

With the development of quantum mechanics, it was found that the orbiting electrons around a nucleus could not be fully described as particles, but needed to be explained by the wave-particle duality.

# The electrons do not orbit the nucleus in the sense of a planet orbiting the sun, but instead exist as standing waves.

# There is always an integer number of electrons orbiting the nucleus.

Overlaying the shield is a gold NASA vector, orbiting the Moon.

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

Hipparcos also suggested that Arcturus is a binary star, with the companion about twenty times dimmer than the primary and orbiting close enough to be at the very limits of our current ability to make it out.

If there are other stars orbiting a black hole, their orbit can be used to determine its mass and location.

Since opposite charges attract via a simple electromagnetic force, the negatively charged electrons that are orbiting the nucleus and the positively charged protons in the nucleus attract each other.

Following the discovery, starting in the 1990s, of other Kuiper belt objects, Pluto began to be seen not as a planet orbiting alone at 40 AU, but as the largest of a group of icy bodies in that region of space.

Shoemaker – Levy 9, at the time captured by and orbiting Jupiter, was located on the night of March 24, 1993, in a photograph taken with the Schmidt telescope at the Palomar Observatory in California.

Orbital studies of the new comet soon revealed that it was orbiting Jupiter rather than the Sun, unlike all other comets known at the time.

Tracing back the comet's orbital motion revealed that it had been orbiting Jupiter for some time.

In Ursula K. Le Guin's science fiction novel The Dispossessed, published 1974, mainstream capitalist and state socialist economies on the planet Urras are contrasted with an anarchist self-managed economy on its orbiting twin Anarres.

Such a " sphere " would be a system of orbiting solar power satellites meant to completely encompass a star and capture most or all of its energy output.

He proposed a system of orbiting structures ( which he referred to initially as a shell ) designed to intercept and collect all energy produced by the Sun.

However, ideas to use orbiting satellites or solar sails employ technology largely already developed.

It remains within the Solar System, orbiting the Sun.

In the novel, as the Star Child gazes upon Earth, he detonates a nuclear weapons satellite orbiting the planet.