The movie Gravity shows the terrifying drama of a major impact event on the International Space Station, but the daily danger faced by the ISS is both smaller and more common. You can clearly see the shields on the ISS (shown above under construction above New Zealand), known as Whipple Shields or Whipple bumpers. The Whipple shield is designed to protect both manned and unmanned spacecraft from hypervelocity (mostly) microscopic particles. Unlike the solid or monolithic shields on early spacecraft, the Whipple shield functions by having a thin shield that absorbs the initial impact and disperses the impact over a larger area thus reducing the force of the impact. With orbital debris travelling at speeds measured in miles per second, the shields play a critical role, as debris the size of a small ball bearing (see below) could be devastating.
The Whipple Shield is named for its designer American astronomer Fred Whipple, born November 5, 1906, died August 30, 2004. In addition to protecting spacecraft, Whipple designed a device for cutting tin foil into chaff to use to fool enemy radar, he came up with the ‘dirty snowball’ model of comet anatomy, discovered several comets and asteroids while working at the Harvard College Observatory for over 60 years. Happy Birthday, Fred!
Today is the birthday of American Astronomer Harlow Shapley (born 1885, died 1972), who made the first accurate estimate of the size of the Milky Way galaxy. Shapley came to astronomy by an interesting route-after dropping out of school with a fifth grade education, he returned years later and finished a six year high school program in two years as class valedictorian. He applied to the University of Missouri to study but the School of Journalism opening was postponed for a year so he decided to study the very first thing in the course directory. He couldn’t pronounce archeology and astronomy was next. Although he is best known for his role in calculating the size of the Milky Way, he stood in opposition to many key astronomers of the day, and was often wrong in his assessment of contemporary theory. Shapley took part in the ‘Great Debate’, also known as the Shapley-Curtis debate in April 1920, a debate pitting him against cosmologist Heber Curtis on the size of the universe held in Wahington DC at the Smithsonian. Shapley and Curtis both presented papers that day about the size of the universe-Shapley contending the Milky Way was the universe, Curtis maintaining that the Milky Way was one of many galaxies. Curtis ultimately was correct.He was also the author of many books on astronomy and had an active role in the formation of the National Academy of Science. To his credit, he was just as often right-his stature and importance as an astronomer cannot be understated.
The first attempt to describe the shape of the Milky Way and the position of the Sun within it was carried out by William Herschel in 1785. Herschel counted the number of stars in different regions of the visible sky and produced a diagram of the shape of the galaxy with the Solar System close to the center, adhering to the Copernican theory of the universe. Herschel’s map looked like this:
In European culture the name Milky Way is comes from its resemblance to a dim ”milky” glowing band arching across the night sky. The term is a translation of the Latin phrase via lactea meaning Milky Way or road, which came from the Ancient Greek γαλαξίας κύκλος (galaktikos kyklos). γαλαξίας (galaxias) which came from the root γαλακτ-, γάλα (milk) became by association the word for all collections of stars we now know as galaxies.
Consider this-our knowledge of the size of the universe is less than 100 years old! Read more about the history from Harlow Shapley himself:
Photo of the Milky Way over Europe courtesy Herb Raab.
When is a discovery not a discovery? In the world of astronomy, that is an excellent question. The first recorded sighting of the Tempel-Tuttle comet occurred on this date, October 26, 1366! But credit for the discovery and identification of the comet would take another 500 years, when it was independently seen and identified by Ernst Wilhelm Leberecht Tempel (December 4, 1821 – March 16, 1889, working in Marseille, France) on December 19, 1865 and by American Civil War veteran and astronomer Horace Parnell Tuttle on January 6, 1866, giving the comet its current name. The Tempel-Tuttle comet is known more for feeding the Leonid Meteor shower in mid-November. The Leonids will peak this year the nights of 16-17 November, set to coincide with a full moon. Despite a fairly short period, returning to earth every 33 years, Tempel-Tuttle has only been recorded a handful of times , notably 1699, 1688, 1965 and 1997.
The connection between the Leonid and Tempel-Tuttle was established in 1981 by In 1981 Donald K. Yeomans of the Jet Propulsion Laboratory who compared and graphed the history of the Leonids against the appearance of Tempel-Tuttle.
The word comet is an English noun like the word planet that comes from an Ancient Greek adjective. The word comet came from Early French (circa 1200) comète via the Ancient Greek (aster) kometes which meant a (star) with long hair. The adjective kometes came from the Ancient Greek word kome meaning a head of hair. Like planet, the word for star was dropped and only the modifier remained. A comet is defined as a celestial body in the solar system, usually with an eccentric orbit, corona and tail. More about comets here:
Top image of Tempel-Tuttle. Lower image of Leonids as seen from space. All images public domain.
Although we now take for granted the long term success of the International Space Station, it wasn’t too long ago that we were totally earthbound. That changed on this day, October 12, 1964 when the Soviet Union launched the Voskhod 1 (Восхо́д), the first manned capsule to carry more than one person into space. The Voskhod program was a proof of concept program to test systems for more ambitious space exploration. The Voskhod program was notable for several firsts: the first multi-person mission to space (Cosmonauts Komarov, Yegorov and Feoktistov in the Voskhod 1) and the first space walk (Belyayev and Leonov in Voskhod 2). The Vostok and Voskhod programs provided the framework for what became the Soyuz program and ultimately the current ISS.
The Russian desire to ‘win’ the Space Race led to many dangerous compromises. The interior of the capsule (shown above) was so cramped that the cosmonauts would not have room for space suits, making the flight extremely dangerous in the event of depressurisation. To insure the engineers paid enough attention to this, head designer Sergei Korolev assigned the lead engineer to fly inside the capsule, therefore motivating him to design the safest capsule possible.
The Russian word Voskhod (Восхо́д) means sunrise and is a combination of the Russian words vos- (from vostok восток) meaning east and xodete (ходить) meaning go or rise.
Image of the Voskhod capsule being assembled courtesy Energiea.
Special thanks to my many Russian teachers over the years: Michael Comenetz, Misha Yurieff, Irina Semionova, Anna Brodski.
On October 6, 1995, astronomers Didier Queloz and Michel Mayor made an announcement that while it had been long anticipated was still stunning: they had discovered the very first exoplanet orbiting around a main sequence star, 51 Pegasi. Although three other exoplanets (one orbiting gamma Cephei, discovered in 1988 by the Canadian astronomers Bruce Campbell, G. A. H. Walker, and Stephenson Yang, confirmed in 2003; and two planets orbiting PSR 1257-12 discovered by radio astronomers Aleksander Wolszczan and Dale Frail in 1992) had been discovered prior to Mayor and Queloz’s announcement, 51 Pegasi was the first exoplanet to be discovered orbiting a main sequence star that is very much like our sun, and therefore thought capable of supporting life.
The official name of this exoplanet is 51 Pegasi b, the lower case b denoting that the star has a companion that is not also a star (as in binary systems), and also referring to its unofficial name of Bellerophon. Bellerophon was the name of the hero from Ancient Greek mythology who tamed the Pegasus. It has since been noted that this planet orbits its star very close and probably has surface temperatures in excess of 1200 degrees, making it unfit for most of the life as we know it on earth.
The word exoplanet is a combination of the Ancient Greek root word prefix exo- meaning outside and the word planet. The word planet entered English as a scientific term from the Old French word planète, which came in turn from Late Latin planeta, which was itself a borrowing from the Ancient Greek adjective (asteres) planetai meaning wandering (stars), from the verb planasthai meaning to wander. It took its modern meaning around 1630. For a great look at the recent discoveries and the scientists studying exoplanets, check out this great book:
Constellation map courtesy Torsten Bronger. Artist’s concept of 51 Pegasi b courtesy Debivort, both used with permission under a Creative Commons 3.0 license.
On this day in 1958, the National Aeronautics and Space Administration opened for space exploration. Signed into law in July 1958 by President Dwight Eisenhower, as the National Aeronautics and Space Act, establishing NASA. NASA absorbed its 46-year-old predecessor NACA ( National Advisory Committee for Aeronautics) intact, taking its 8,000 employees, its annual budget of $100 million, and three major research laboratories. A NASA seal was approved by President Eisenhower in 1959.
Since that day,NASA’s contributions to the United States and humanity in general have been vast-we have walked on the moon, sent probes out beyond the heliosphere, peered 13-16 billion light years out to the edge of the universe.
Any one of these accomplishments would have been significant on their own merits-the fact that a single agency has overseen such a staggering array of projects is simply amazing.
Happy Birthday, NASA!
NASA logos courtesy NASA.
400 years ago, a great arms race began in the scientific community: using the newly developed technology afforded by the telescope, astronomers and natural scientists stayed up night after night training their new instruments on the sky. Few were as prolific or as careful (or talented) as Galileo Galilei who 400 years ago first saw the planet Neptune through a telescope on December 28, 1612.
The telescope was immediately recognized as the most significant technological revolution in astronomy. Galileo noted the object but failed to recognize its significance, and Neptune disappeared for another 234 years, when it was predicted by French astronomer Urbain LeVerrier. A second arms race began when English, French and German scientists all raced to find the planet predicted by the perturbations in Uranus’ orbit. By this time the telescope was in regular use by both scientists and talented amateurs around the world as scientists stayed up night after night searching for discoveries.
The prediction of a new planet was soon confirmed by German astronomer Johann Gottfried Galle just one year after he finished his Ph.d dissertation which he had sent to LeVerrier for comments. Galle found Neptune first on September 23, 1846, though James Challis had both spotted it and noted it but failed to recognize it as a planet due to using outdated star maps. A minor battle then ensued when LeVerrier suggested the name Leverrier for the new planet-and had English astronomers immediately insist that the recently discovered Uranus be named Herschel after its discoverer, the Anglo German astonomer William Herschel, who for his part wanted to call Uranus after his patron King George III of England. Galle first proposed Janus (the Roman two-faced god) and Challis proposed Oceanus. Ultimately consensus was found by continuing with the theme of naming planets after Greek and Roman gods, as the west had done since antiquity, and the planet was named Neptune. Irregularities in Neptune’s orbit led to a third race to discover any satellites that might be orbiting, and 17 days later Neptune’s first moon was discovered by amateur English astonomer and beer magnate William Lassell on October 10, 1846 and named Triton.
Neptune’s next two moons were discovered in the 1940s but it wasn’t until the Voyager spacecraft passed Neptune that an additional 5 moons were found. Neptune now has 14 recognized satellites, the most recent of which remains un-named, first spotted in 2004.
Images of Neptune and the Great Dark Spot and all moons courtesy NASA, all other images in the public domain.
On September 19, 1848, astronomers William Cranch Bond, George Phillips Bond and William Lassell discovered the first non-sperical, irregular moon orbiting the planet Saturn, which they named Hyperion (Ὑπερίων) after the Greek god/titan who was the brother of Cronus (the Greek equivalent of Saturn). Looking like a giant potato in the sky,
Hyperion is the second largest non-sperical satellite discovered, measuring 360.2×266×205.4 km. Lassell and Bond both observed Hyperion independently of each other only days apart, and only a year after William Herschel had published Results of Astronomical Observations made at the Cape of Good Hope in which he suggested the name scheme for the first seven moons of Saturn, and which Lassell and Bond used when they proposed Hyperion.
Images of Hyperion courtesy NASA/Cassini.