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A sense of scale 3
FEATURE: Space shuttles 11
The Sun 15
a sense of scale
Largest spiral galaxy Discovered in 1986, from photographs taken by the Anglo-Australian astronomer David Malin, and later named after him, Malin 1 is a spiral galaxy some 1.1 billion light-years away. In terms of its diameter, it is the largest known spiral galaxy in the Universe, measuring around 650,000 light-years across-several times the size of our Milky Way, which has a diameter of around 100,000 light-years. Malin 1 contains some 50 billion suns' worth of free- floating hydrogen.
Largest globular cluster Omega Centauri, in the southern constellation of Centaurus, is the most massive of the roughly 140 globular clusters surrounding our galaxy. Consisting of several million stars with a combined mass equivalent to 5 million suns, it is visible to the naked eye as a hazy star. However big this might seem, it would still take around a thousand Omega Centauris to equal just one spiral galaxy such as the galaxy in which we live, the Milky Way.
Largest star Due to the physical difficulties in directly measuring the size of a distant star, not all astronomers agree on the largest star, but the most likely candidate is VY Canis Majoris, a red supergiant some 5,000 light-years away. Estimates of its size give it a diameter of between 1.55 and 1.86 billion miles (2.5-3 billion km). If placed at the center of the Solar System, its outer surface would reach beyond the orbit of Jupiter.
Largest star with a planet In January 2003 astronomers announced their discovery of a planet orbiting the orange giant star HD 47536. This star is expanding at the end of its life and currently measures around 20.5 million miles (33 million km, or 23 times the size of the Sun) across. The planet is some 186 million miles (300 million km) from its star but will eventually be consumed in a few tens of millions of years as the star continues to expand into a red giant.
ILargest extrasolar planet Discovered in 2006, TrES-4 is an extra solar planet some 1,400 light-years away, orbiting its parent star GSC 02620-006648 once every 3.5 days. It was discovered using the transit method, where the planet eclipses its star during its short orbit as seen from Earth. With a diameter of around 150,000 miles (240,000 km), it is some 1.7 times the size of Jupiter.
Largest dwarf planet The icy world Eris was discovered in January 2005. It has a highly elliptical orbit, with its distance from the Sun ranging from between 3.4 and 9.07 billion miles (5.6 and 14.6 billion km), and a diameter of around 1,490 miles (2,400 km). Before the reclassification of Pluto as a dwarf planet, Eris was regarded by many as the tenth planet of the Solar System. Eris has a small moon, Dysnomia, around 217 miles (350 km) across.
Largest Kuiper Belt Object The Kuiper Belt is the cloud of frozen gases and debris at the edges of our Solar System around 55 AU (5 billion miles; 8.1 billion km) from the Sun. The Kuiper Belt object 50000 Quaoar measures around 800 miles (1,300 km) across and was discovered by Chad Trujillo and Mike Brown (both U.S.A.) at Caltech, Pasadena, California, U.S.A., on June 4, 2002. The object, originally dubbed 2002 LM60, is named after a creation god of the Tongva tribe- the original inhabitants of the Los Angeles area. It orbits the Sun at a distance of around 4 billion miles (6 billion km) and has an orbital period of 288 years.
Largest asteroid in the asteroid belt Among all the objects in the asteroid belt between Mars and Jupiter, Ceres is the largest, with an average diameter of 584.7 miles (941 km). Discovered by Giuseppe Piazzi in Palermo, Sicily, on January 1, 1801, Ceres is large enough to have an almost spherical shape. It is classified as the smallest dwarf planet and is due to be visited by NASA's Dawn probe in 2015.
HLargest asteroid visited by spacecraft First discovered in 1885, 253 Mathilde, like Ceres, is found in the Asteroid Belt. It measures 41 x 29 x 28 miles (66 x 48 x 46 km) and became the third and largest asteroid to be encountered by a spacecraft in June 1997, when NASA's NEAR Shoemaker spacecraft passed it.
Least round planet A combination of its low density (less than water) and rapid rotation (10.6 hours) gives Saturn the most oblate shape among the planets. Its equatorial diameter is 74,897.5 miles (120,536 km) while its polar diameter is just 67,560 miles (108,728 km).
HLongest-lasting lightning storm A lightning storm in Saturn's upper atmosphere raged for more than eight months in 2009. Monitored by the Cassini spacecraft, the storm, with a diameter of several thousand miles, caused lightning flashes in Saturn's atmosphere around 10,000 times the intensity of their terrestrial counterparts.
HLargest eruptive ice plumes Active cryovolcanism on Enceladus, Saturn's sixth-largest moon, had been predicted by scientists ever since the encounters by the two Voyager spacecraft in the early 1980s had revealed the geologically young surface of this icy moon. In 2005, observations from the Cassini spacecraft showed immense plumes of water ice above the moon's south pole. They are formed by the eruption of pressurized water reservoirs beneath the ice, forced to the surface by volcanic activity. They are at least as tall as the moon's 313-mile (505-km) diameter.
HClosest moon to Saturn Discovered in July 2009 using observations from the Cassini spacecraft, S/2009 S 1 is a tiny moon just 985 ft. (300 m) across that orbits Saturn at a distance of just 35,251 miles (56,732 km), less than the radius of the planet. It orbits within the outer B Ring and was discovered using the shadow it cast across the rings themselves.
HOutermost discrete ring The most outwardly discrete ring, as opposed to a diffuse dust disk, is the contorted F Ring, with an orbital radius of 87,600 miles (141,000 km). It lies some 2,500 miles (4,000 km) beyond the edge of the main ring system and is probably the most dynamically active ring in the Solar System. Just a few hundred miles wide, the F Ring is thin and held in place by two shepherd moons, Pandora and Prometheus, whose gravitational interactions with the ring particles produce twisted knots within the ring that can change appearance in just a few hours.
Tallest ridge in the Solar System Observations of Saturn's moon Iapetus by the NASA/ESA spacecraft Cassini-Huygens on December 31, 2004, revealed a ridge at least 800 miles (1,300 km) long, reaching an altitude of around 12 miles (20 km) above the surface. Iapetus is just 890 miles (1,400 km) across.
Largest chaotically rotating object Saturn's moon Hyperion measures 254 x 161 x 136 miles (410 x 260 x 220 km) and is the largest highly irregularly shaped body in the Solar System. It is one of only two bodies in the Solar System discovered to have completely chaotic rotation, tumbling in its orbit around Saturn. The other is asteroid 4179 Toutatis, measuring 2.7 x 1.5 x 1.1 miles (4.5 x 2.4 x 1.9 km).
Closest moons to each other Janus and Epimetheus share the same average orbit some 56,500 miles (91,000 km) above Saturn. As their orbital paths are only 31 miles (50 km) apart, one of the moons is always catching the other up. Every four years they come within 6,200 miles (10,000 km) of each other and swap orbits, before drifting apart again.
Satellite with the thickest atmosphere Saturn's large moon Titan has the thickest atmosphere of any moon in the Solar System, exerting a surface pressure of 1.44 bar. It consists mainly of nitrogen gas and is the most similar atmosphere to our own in the Solar System.
The Space Shuttle-or, more accurately, the Shuttle Transportation System (STS)-made its first test flights in 1981, and orbital missions began the following year. It is the world's first-and to date only-spacecraft to make multiple orbital flights and landings.
Now, 30 years later, NASA has announced the retirement of the space shuttle program. With its end in sight, we take a look at the shuttle's record-breaking history and its major achievements.
IMost reused spacecraft NASA's space shuttle Discovery was last launched on April 5, 2010, beginning its 38th spaceflight, STS-131. Discovery, the third orbiter in the shuttle fleet, first flew in August 1984.
Longest shuttle flight The lengthiest shuttle flight was by Columbia and its crew of five astronauts during the STS-80 mission. Launched on November 19, 1996, it had 17 days 15 hr. 53 min. 26 sec. of mission elapsed time.
Largest shuttle crew The shuttle mission with the largest crew to date was STS-61-A, which launched on October 30, 1985, carrying eight astronauts on board Challenger. This flight carried the West German Spacelab D-1 laboratory. The flight lasted 7 days 44 min. 51 sec.
Largest door Each of the four doors in the NASA Vehicle Assembly Building near Cape Canaveral, Florida, U.S.A., is 460 ft. (140 m) high, as tall as a 35-story building. Their massive size was originally to allow fully assembled Saturn V rockets to pass through them.
HMost people on a spacewalk The first flight of Endeavour on May 7, 1992, was to repair the failing Intelsat VI satellite. Retrieving the satellite proved problematic until Pierre Thuot, Richard Hieb, and Thomas Akers (all U.S.A.) performed a spacewalk and were able to capture Intelsat VI by hand. In the meantime, mission commander Daniel Brandenstein (U.S.A.) maneuvered Endeavour to within a few feet of the stricken satellite. This is the only occasion in history that three people have walked in space at the same time.
HFirst manned maiden spaceflight The first ever shuttle launch was a test flight by astronauts John Young and Robert Crippen (both U.S.A.) on April 12, 1981. This was the first time a new spacecraft system had ever flown in space without a prior unmanned spaceflight.
HHeaviest glider The heaviest shuttle landing was Columbia during the STS-83 mission, which touched down on April 8, 1997, with a mass of 213,060 lb. (96,642 kg). To return to Earth, the shuttle fires its orbital maneuvering engines to slow down and decrease its altitude, and uses friction to reduce speed in the upper atmosphere. From then on, the landing sequence is unpowered, with the shuttle acting as a glider, performing a series of high-altitude turns to dissipate speed, and eventually approaching the runway and touching down with the rear wheels first.
HHeaviest component At liftoff, the space shuttle consists of the orbiter itself, the external fuel tank that feeds its main engines, and two solid rocket boosters attached to the tank that provide additional thrust. The heaviest component at liftoff is the tank, weighing 1,680,000 lb. (760,000 kg).
Heaviest payload launched The Chandra X-ray Observatory was launched by Columbia on July 23, 1999. With a mass of 50,161 lb. (22,753 kg), this was the heaviest satellite that has ever been launched by the space shuttle.
HFirst flyby of the Sun's poles The joint NASA/ESA Ulysses spacecraft was launched from the space shuttle Discovery in 1990. It headed out to Jupiter, where it used a gravitational slingshot to send it into a polar orbit around the Sun, from where it has directly observed both solar poles. The spacecraft ceased operations on June 30, 2009.
Largest sunspot group On April 8, 1947, the largest sunspot group ever identified was found in the Sun's southern hemisphere. At its greatest length, it measured 187,000 miles (300,000 km), with a maximum width of 90,000 miles (145,000 km). It was roughly 36 times greater than the surface area of the Earth and was even visible to the naked eye, close to sunset.
HLongest-lasting sunspot group Between June and December 1943, a group of sunspots was observed to last for 200 days. The smallest sunspots, known as pores, and less than 1,553 miles (2,500 km) across, can last less than one hour.
HLongest and shortest solar cycles The solar cycle is a periodic change in the number of sunspots on the surface of the Sun and relates directly to solar magnetic activity. It was first discovered in 1843 and, by examining older observations of sunspots, astronomers now have data on sunspot activity going back to the early 17th century. The cycle lasts an average of 11 years, with the longest so far ending in 1798 having lasted 13.7 years, and the shortest ending in 1775 having lasted just nine years.
HBiggest object in the Solar System The Sun has a mass 332,900 times greater than that of Earth, and a diameter of 865,000 miles (1,392,000 km). It accounts for 99.86% of the mass of the whole Solar System.
Closest approach to the Sun by a spacecraft The unmanned spacecraft Helios 2 approached within 27 million miles (43.5 million km) of the Sun, carrying both U.S. and West German instrumentation, on April 16, 1976.
Due for launch in 2015, NASA's Solar Probe+ will attempt to study the Sun from as close as 3.9 million miles (6.2 million km), from within the Sun's outer atmosphere or corona. Traveling at a speed of 125 miles/sec. (200 km/sec.), the spacecraft will have to survive temperatures of up to 2,600ºF (1,420ºC).
HStrongest geomagnetic storm On September 1, 1859, at 11:18 a.m., British astronomer Richard Carrington observed two blinding explosions occurring on the surface of the Sun. The following dawn, all over the world the skies were ablaze with auroras caused by the charged particles from the eruptions interacting with Earth's magnetosphere, having taken just 18 hours to cross the space between the Sun and the Earth (the journey normally takes three or four days).
The study of ice cores suggest that events of this magnitude occur roughly every 500 years. The magnetic disruptions caused by the "Carrington Event" affected telegraph systems all over Europe and North America.
Most destructive geomagnetic storm The "Great Geomagnetic Storm" of March 13, 1989, was the most destructive geomagnetic storm ever recorded. The record-breaking event was classified G5 (the most severe rating) on the space weather scale. The result of an abnormally strong solar wind, it caused large-scale disruption to the power grid in Canada and the U.S.A., and even changed the orbit of a satellite. The power outages-caused by failures at the Hydro-Québec systems in Canada-saw 6 million people losing electricity for nine hours.
HNearest star The pioneering work of Father Angelo Secchi (Italy, 1818-78) in spectroscopy led to his classification scheme for stars, and to his conclusion that our own Sun was a star and not a phenomenon unique to the Solar System. At just 93,000,000 miles (149,000,000 km) from Earth, the Sun is astronomically close. The next nearest star, Proxima Centauri, is 4.2 light years away, or 24,000,000,000,000 miles (40,000,000,000,000 km).