Saturn Saturn's interior is probably composed of a core of iron, nickel and rock (silicon and oxygen compounds), surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium and an outer gaseous layer.[15] The planet exhibits a pale yellow hue due to ammonia crystals in its upper atmosphere. Electrical current within the metallic hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is weaker than Earth's magnetic field but has a magnetic moment 580 times that of the Earth due to Saturn's larger body radius. Saturn's magnetic field strength is around one-twentieth the strength of Jupiter's.[16] The outer atmosphere is generally bland and lacking in contrast, although long-lived features can appear. Wind speeds on Saturn can reach 1,800 km/h (1,100 mph), faster than on Jupiter, but not as fast as those on Neptune.[17] Physical characteristics Composite image roughly comparing the sizes of Saturn and Earth Atmosphere
Black hole A black hole is defined as a region of spacetime from which gravity prevents anything, including light, from escaping.[1] The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole.[2] Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return. The hole is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics.[3][4] Quantum field theory in curved spacetime predicts that event horizons emit radiation like a black body with a finite temperature. This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater. Objects whose gravity fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. History General relativity
Mercury (planet) Mercury is gravitationally locked and rotates in a way that is unique in the Solar System. As seen relative to the fixed stars, it rotates exactly three times for every two revolutions[b] it makes around its orbit.[13] As seen from the Sun, in a frame of reference that rotates with the orbital motion, it appears to rotate only once every two Mercurian years. An observer on Mercury would therefore see only one day every two years. Because Mercury's orbit lies within Earth's orbit (as does Venus's), it can appear in Earth's sky in the morning or the evening, but not in the middle of the night. Internal structure Internal structure of Mercury: 1. Mercury's density can be used to infer details of its inner structure. Mercury's core has a higher iron content than that of any other major planet in the Solar System, and several theories have been proposed to explain this. Alternatively, Mercury may have formed from the solar nebula before the Sun's energy output had stabilized. Surface geology
Phobos (moon) Phobos (systematic designation: Mars I) is the larger and closer of the two natural satellites of Mars. Both moons were discovered in 1877. Phobos has dimensions of 27 × 22 × 18 km,[1] and is too small to be rounded under its own gravity. Faint dust rings produced by Phobos and Deimos have long been predicted but attempts to observe these rings have, to date, failed.[23] Recent images from Mars Global Surveyor indicate that Phobos is covered with a layer of fine-grained regolith at least 100 meters thick; it is hypothesized to have been created by impacts from other bodies, but it is not known how the material stuck to an object with almost no gravity.[24] The unique Kaidun meteorite is thought to be a piece of Phobos, but this has been difficult to verify since little is known about the detailed composition of the moon.[25][26] Labeled Map of Phobos - Moon of Mars (USGS).[30] Tidal deceleration is gradually decreasing the orbital radius of Phobos.
Uranus Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Uranus is similar in composition to Neptune, and both are of different chemical composition than the larger gas giants Jupiter and Saturn. For this reason, astronomers sometimes place them in a separate category called "ice giants". Uranus's atmosphere, although similar to Jupiter's and Saturn's in its primary composition of hydrogen and helium, contains more "ices" such as water, ammonia, and methane, along with traces of hydrocarbons.[12] It is the coldest planetary atmosphere in the Solar System, with a minimum temperature of 49 K (−224.2 °C), and has a complex, layered cloud structure, with water thought to make up the lowest clouds, and methane the uppermost layer of clouds.[12] In contrast, the interior of Uranus is mainly composed of ices and rock.[11] History Discovery The power I had on when I first saw the comet was 227. Naming Name Axial tilt
Pulsar The precise periods of pulsars makes them useful tools. Observations of a pulsar in a binary neutron star system were used to indirectly confirm the existence of gravitational radiation. The first extrasolar planets were discovered around a pulsar, PSR B1257+12. History of observation[edit] Discovery[edit] The first pulsar was observed on November 28, 1967, by Jocelyn Bell Burnell and Antony Hewish.[1][2][3] They observed pulses separated by 1.33 seconds that originated from the same location on the sky, and kept to sidereal time. The word "pulsar" is a contraction of "pulsating star",[7] and first appeared in print in 1968: An entirely novel kind of star came to light on Aug. 6 last year and was referred to, by astronomers, as LGM (Little Green Men). Milestones[edit] In 1974, Joseph Hooton Taylor, Jr. and Russell Hulse discovered for the first time a pulsar in a binary system, PSR B1913+16. In 1992, Aleksander Wolszczan discovered the first extrasolar planets around PSR B1257+12.
Earth Earth is the third planet from the Sun. It is the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the world or the Blue Planet.[23] Earth formed approximately 4.54 billion years ago, and life appeared on its surface within its first billion years.[24] Earth's biosphere then significantly altered the atmospheric and other basic physical conditions, which enabled the proliferation of organisms as well as the formation of the ozone layer, which together with Earth's magnetic field blocked harmful solar radiation, and permitted formerly ocean-confined life to move safely to land.[25] The physical properties of the Earth, as well as its geological history and orbit, have allowed life to persist. Name and etymology In general English usage, the name earth can be capitalized or spelled in lowercase interchangeably, either when used absolutely or prefixed with "the" (i.e. Heat
Mercury (planet) First planet from the Sun Mercury's sidereal year (88.0 Earth's day) and sidereal day (58.65 Earth's day) is in a 3:2 ratio. This phenomenon is called spin–orbit resonance and sidereal here means "relative to the stars". Consequently, one solar day (sunrise to sunrise) on Mercury lasts for around 176 Earth's day - twice the planet's sidereal year. Combined with its high orbital eccentricity, the planet surface has widely varying sunlight intensity and temperature, with the equator regions range from −170 °C (−270 °F) at night to 420 °C (790 °F) during sunlight. Nomenclature Physical characteristics Internal structure Surface geology Impact basins and craters Overhead view of Caloris Basin Perspective view of Caloris Basin – high (red); low (blue) Plains Compressional features Volcanism Surface conditions and exosphere Magnetic field and magnetosphere Orbit, rotation, and longitude Orbit of Mercury (2006) Animation of Mercury's and Earth's revolution around the Sun Longitude convention Observation Notes
Mars Animation of Mars' rotation from the vantage of an observer who moves south, then north, to hover over both poles, showing the planet's major topographic features. Mars is currently host to five functioning spacecraft: three in orbit – the Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter – and two on the surface – Mars Exploration Rover Opportunity and the Mars Science Laboratory Curiosity. Defunct spacecraft on the surface include MER-A Spirit and several other inert landers and rovers such as the Phoenix lander, which completed its mission in 2008. Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Physical characteristics Size comparison of Earth and Mars. Internal structure Surface geology During the Solar System's formation, Mars was created as the result of a stochastic process of run-away accretion out of the protoplanetary disk that orbited the Sun. This Mars rock revealed its bluish-gray interior to Mars Science Laboratory[40] Soil
Apollo Photographic Support Data Venus Venus is a terrestrial planet and is sometimes called Earth's "sister planet" because of their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest in size to Earth). However, it has also been shown to be very different from Earth in other respects. It has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide. The atmospheric pressure at the planet's surface is 92 times that of Earth's. Physical characteristics Venus is one of the four terrestrial planets in the Solar System, meaning that, like Earth, it is a rocky body. Geography The Venusian surface was a subject of speculation until some of its secrets were revealed by planetary science in the 20th century. Most Venusian surface features are named after historical and mythological women.[26] Exceptions are Maxwell Montes, named after James Clerk Maxwell, and highland regions Alpha Regio, Beta Regio and Ovda Regio. Surface geology
Burn notice: NASA discovers that fireproof materials ignite in space Still frames showing a piece of cotton-fiberglass, similar to the cotton civilian clothing worn by astronauts, burning from bottom-to-top during a space station experiment (Credit: Paul Ferkul/NASA/BASS). High above the Earth, astronauts aboard the International Space Station are playing with fire — very carefully. By lighting controlled fires and watching them burn, the Expedition 35 team is learning how to prevent accidental blazes from breaking out aboard the station and other spacecraft — a nightmare scenario that could put not only lives, but the very future of human spaceflight at risk. "in space, [fireproofing] changes." Concerns about accidental fire in space are valid, given that in 1997, a malfunction aboard the Russian Mir space station ignited a small blaze so hot it melted parts of the metal interior. Acrylic sphere sample burning aboard the International Space Station as part of Paul Ferkul's BASS experiment (Credit: NASA/BASS/Flickr). "This type of situation could occur."