Astronomy Dictionary

KELVIN Lord Kelvin (William Thomson, 1824 - 1907) designed the Kelvin scale, in which 0 K is defined as absolute zero and the size of one degree is the same as the size of one degree Celsius. Water freezes at 273.16 K; water boils at 373.16 K. For more information on Kelvin, click here.

Kelvin Celsius Fahrenheit Water boils 373.16K 100°C 212°F Water freezes 273.16K 0°C 32°F Absolute zero 0K -273.16°C -459.7°F KELVIN TEMPERATURE SCALE Kelvin is a temperature scale designed so that 0K is defined as absolute zero and the size of one unit is the same as the size of one degree Celsius. Water freezes at 273.16K; water boils at 373.16K. This temperature scale was designed by Lord Kelvin (William Thomson, 1824 - 1907). [ K = C + 273°, F = 9/5C + 32°].

KELVIN WAVE The Kelvin wave is a gentle but huge swell of warm water in the Pacific Ocean. This mass of water is a few degrees warmer than surrounding water, is only 5-10 cm high, but is hundreds of kilometers wide.

KEPLER, JOHANNES Johannes Kepler (1571-1630) was a German mathematician who realized that the planets go around the sun in elliptical orbits. He formulated what we now call "Kepler's Three Laws" of planetary motion that mathematically describe the elliptical orbits of celestial objects. For a few years he worked with Tycho Brahe.

KEPLER'S FIRST LAW OF PLANETARY MOTION Kepler's First Law of Planetary Motion states that the orbits of the planets are ellipses with the sun at one focus of the ellipse.

KEPLER'S SECOND LAW OF PLANETARY MOTION Kepler's Second Law of Planetary Motion states that a line from a planet to the sun will sweep out equal areas in equal times. The planet moves more slowly when it is farther from the sun and faster when it is near it. (This is equivalent to the conservation of angular momentum.)

KEPLER'S THIRD LAW OF PLANETARY MOTION Kepler's Third Law of Planetary Motion states that T2 is proportional to a3, where T is the orbital period of a planet (its year) and a is the semi-major axis of the ellipse.

KILOGRAM A kilogram (kg) is a unit of mass defined as the weight of one liter of water. One kilogram is equivalent to 1,000 grams or 2.2 pounds.

KIRCHOFF, GUSTAV Gustav Kirchoff (1824-1887) was a German physicist who realized that each element gave off a characteristic color of light when heated to incandescence. When separated by a prism, the light for each element had a specific pattern of wavelengths. Kirchoff, together with Bunsen, used his techniques to discover two new elements, cesium (1860) and rubidium (1861). Kirchoff found that when light shines through a gas, the gas absorbs some of the light, the same wavelengths of light that it would emit when heated. He applied his techniques to the Sun, explaining Fraunhofer lines. He also found that incandescent solids, liquids, and compressed gases emit a continuous spectrum.

KIRKWOOD GAPS The Kirkwood gaps are radial gaps in the asteroid belt. These gaps are orbital radii where the gravitational forces from Jupiter do not let asteroids orbit (they would be pulled into Jupiter). For example, an orbit in which an asteroid orbited the Sun exactly three times for each Jovian orbit would experience great gravitational forces each orbit, and would soon be pulled out of that orbit. There is a gaps at 3.28 AU (which corresponds to 1/2 of Jupiter's period), another at 2.50 AU (which corresponds to 1/3 of Jupiter's period), etc. The Kirkwood gaps are named for Daniel Kirkwood who discovered them in 1866.

KLEOPATRA 216 Kleopatra is a bone-shaped asteroid. Kleopatra is about 135 miles (217 kilometers) long and about 58 miles (94 kilometers) wide. This unusual asteroid was discovered and named in 1880, but its shape was only discovered in 2000, using radar images from the Arecibo telescope.

KLET OBSEVATORY The Klet Observatory is a state supported research institution located in the Czech Republic (Southern Bohemia). This astronomical observatory is located on Klet mountain (at 1070 meters altitude), southwest of the town of Ceske Budejovice. Telescopes include a 0.57-m f/5.2 reflector, a 0.63-m Maksutov telescope, and a 1.02-m telescope.

KM Km is short for kilometer or kilometers.

KNOTS Saturn's outermost ring, the subdivided "F" ring, has many visible knots or clumps of matter. These knots may be clumps of particulate ring material or tiny orbiting moons of Saturn.

KUIPER BELT The Kuiper belt is a region beyond Neptune in which at least 70,000 small objects (KBO's) orbit, including Quaoar and Sedna. This belt is located from 30 to 50 (?) A.U.'s and was discovered in 1992. The Kuiper belt may be the source of the short-period comets (like Halley's comet). The Kuiper belt was named for the Dutch-American astronomer Gerard P. Kuiper, who predicted its existence in 1951.

KUIPER, G. P. Gerard Peter Kuiper (1905-1973) was a Dutch-American astronomer who predicted the existence of the Kuiper belt in 1951. In 1948, Kuiper discovered and named Miranda, a moon of Uranus and Neptune's second moon, Nereid. Kuiper did much pioneering research on moons, planetary atmospheres, and planet and moon formation.

Astronomy Dictionary

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