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---- 1705 ---- In 1705 Edmund Halley calculated the orbits of comets observed in 1531 and 1607 and 1682. He extrapolated his calculations and predicted the comets return in 1758. Now it is called Halley's Comet.
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- Edmond Halley was an English astronomer living from the year 1656 to 1742. He was the son of a wealthy businessman. In 1676, he set off to record the stars in the southern hemisphere, cataloging 341 southern stars. Halley's father was murdered in 1684. He inherited a large amount of money. In 1703, he became professor of geometry at Oxford. By 1705 he had defined the orbits for 24 comets. One record of a comet was from 1450, 1531, 1607, 1682, which convinced Halley that it was a single comet on a 75 year orbit. He predicted its return in 1758. Since then Halley’s Comet has arrived in 1835, 1910, 1986.
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----- 1687 ---- In 1687 Isaac Newton published the laws of motion and gravity.
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----- 1781 ---- In 1781 William Herschel discovered the planet Uranus.
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- Sir William Herschel lived from 1738 to 1822. He was born in Hanover, Germany. His father was a musician in the Hanoverian Army. His parents sent him to England in 1757 to avoid the Seven Years War. He and his sister ground lenses to construct telescopes. In 1781 his systematic studies of stars made the discovery of the planet Uranus. He went on to discover some 800 binary stars. In 1787, he discovered two of the moons orbiting Uranus. He discovered Enceladus and Mimas moons orbiting Saturn. He measured the temperature of colors coming from the Sun and discovered infrared as a hottest temperature with no color at all. It was invisible light beyond the red end of the spectrum His son John Herschel became another renowned astronomer.
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----- 1846 ---- In 1846 Neptune was discovered.
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----- 1838 ---- In 1838, the distance to the star 61 Cygni was calculated by Frederick Bessel. He measured the angle parallax as it is shifted in the sky over six months of Earth's orbit.
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- Friedrich Wilhelm Bessel lived from 1784 to 1846. In 1804 at the age of 20 Bessel recalculated the orbit for Halley’s Comet. In 1810 he became the director of the Konigsberg Observatory. In 1818 he published a star catalogue containing 50,000 stars. He was the first to use parallax to calculate the distance to a star 61 Cygni. His answer was that it was 35,000,000,000,000 miles away. ( 6 lightyears ). He calculated the masses of Jupiter and Saturn. The Bessel math functions are canonical solutions to differential equations. The equations are used to study wave propagations and work for exponentially growing and decaying functions He died of cancer in 1846.
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----- 1862 ---- In 1862 the first White Dwarf star was discovered around Sirius B. It was a dim star the mass of the Sun, but, compressed to the volume of the Earth. How this happened was not understood until the 1900s.
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----- 1860 ---- In 1860 William Higgins used spectroscopy to discover calcium, iron, magnesium, and sodium on the stars Aldebaran and Betelgeuse. These were the same elements found in the Sun.
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----- 1910 ---- In 1910 Harlow Shapley discovered the center of the Milky Way 25,000 lightyears away. He discovered 93 globular star clusters in a spherical distribution around the constellation Sagittarius.
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- Harlow Shapley lived from 1885 to 1972 he was born in Nashville Missouri. In 1903 attending University Missouri in 1913 attending Princeton. In 1914 he joined the Wilson Observatory in California and applied Henrietta Leavitt's luminosity to Cepheid Variable stars in globular clusters. He calculated distances to the stars and is credited for presenting a realistic picture of our galaxy’s true size.
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----- 1910 ---- In 1910 the H-R diagram was created that plotted the intrinsic brightness of stars as a function of their color. Color was the surface temperature of the star. The plot was a straight diagonal line.
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----- 1912 ------ In 1912 Henrietta Leavitt developed a method to gauge nearby universal distances using Cepheid variables stars. The brightness of the stars varied in a relationship of the luminosity oscillations to the star’s intrinsic brightness. These Cepheid stars were in the Small Megellanic Cloud , one of Milky Way's satellite galaxies.
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----- 1916 ---- In 1916 Elbert Einstein published the general theory of relativity to explain gravity as a warping of space time.
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----- 1923 ---- In 1923 Edwin Hubble used Cepheid Variable stars in M 31, the Andromeda galaxy to become the first galaxy named after the Milky Way.
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----- 1929 ---- In 1929 Edwin Hubble discovered that the father galaxies were away from us the faster they were receding. The Hubble constant for the universe expansion is 47,000 miles per hour per every 1,000,000 lightyears distance.
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- Edwin Hubble lived from 1889 to 1953. He was born in Marshfield Missouri. He was a Rhodes scholar at Oxford in 1910. He worked at the Mount Wilson Observatory using their 100 inch telescope in 1919. Shapley had worked out the dimensions of our galaxy. In 1924 identified Cepheid Variable stars in the Andromeda Galaxy, at that time it was referred to as a nebula. This began Hubble study of the galaxies beyond our own Milky Way Galaxy. By measuring radio velocities he proposed that the speed at which galaxies were received from us was directly proportional to their distances. This meant the universe was expanding. He further concluded that the Observable Universe was 26,000,000,000 lightyears across. During World War II Hubble was given the 200 inch telescope at Mount Palomar to continue his studies
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RSVP, with comments, suggestions and corrections. An index of all reviews is available. Some reviews are at: -------------------- http://jdetrick.blogspot.com
,or: email request for copies to: ------- jamesdetrick@comcast.net
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------ www.twitter.com or cell: 707-536-3272 ------ Sunday, December 8, 2013
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