astronomy

GALILEO GALILEIItalian astronomer

Galileo Galilei provided a number of scientific insights that laid the foundation for future scientists.

His investigation of the laws of motion and improvements on the telescope helped further the understanding of the world and universe around him.

Both led him to question the current belief of the time that all things revolved around the Earth.

In 1609, he first learned of the existence of the spyglass, which excited him. He began to experiment with telescope-making, going so far as to grind and polish his own lenses. 

His telescope allowed him to see with a magnification of eight or nine times. In comparison, spyglasses of the day only provided a magnification of three.

It wasn't long before Galileo turned his telescope heavenward. He was the first to see craters on the moon, discover sunspots, and track the phases of Venus. The rings of Saturn puzzled him, appearing as lobes and vanishing when they were edge-on - but he saw them, which was more than can be said of his contemporaries. And recent research seems to imply he discovered Neptune two centuries before it was officially known.

Of all of his telescope discoveries, he is perhaps most known for his discovery of the four most massive moons of Jupiter: Io, Ganymede, Europa, and Callisto, now called the Galilean moons. When NASA sent a mission to Jupiter in the 1990s, it was called Galileo in honor of the famed astronomer.

WILLIAM HERSCHELBorn in Germany as

Friedrich Wilhelm Herschel, the astronomer was the son of Anna Ilse Moritzen and Issak Herschel. His father was a military musician, and young William played in the same band in his early years. In 1759, Herschel left Germany for England, where he taught music before becoming an organist.

March 13, 1781, Herschel noticed a small object that, over the course of several nights, was slowly moving across the sky. At first he thought he had found a comet, but further observation revealed that the object was a planet. Herschel lobbied to name the new body 'Georgium Sidus', after King George III, but it was eventually named Uranus after the Greek god of the sky.

In 1789, Herschel finished construction on 40-foot-long (12 meters) telescope, the largest of the day. But the unwieldy instrument came with a number of problems, and Herschel tended to use the smaller, 20-foot (6-meter) telescope.Herschel discovered several moons around the gas giants. In 1787, he discovered two moons around Uranus: Titania and Oberon. In 1789, using his larger telescope, he found Saturn's sixth and seventh moons, Enceladus and Mimas.

Edmund halleyEdmond (or

Edmund) Halley was an English scientist who is best known for predicting the orbit of the comet that was later named after him. Though he is remembered foremost as an astronomer, he also made significant discoveries in the fields of geophysics, mathematics, meteorology and physics.

HALLEY’S COMETContinuing his work in

observational astronomy, Halley published "A Synopsis of the Astronomy of Comets" in 1705. In this work, he showed that comet sightings of 1456, 1531, 1607 and 1682 were so similar that they must have been the same comet returning. He predicted that it would return in 1758.

Halley died Jan. 14, 1742, in Greenwich, England. He did not survive to see the return of what later was named Halley's Comet, on Christmas Day in 1758

Halley's Comet is arguably the most famous comet. It is a "periodic" comet and returns to Earth's vicinity about every 75 years, making it possible for a human to see it twice in his or her lifetime. The last time it was here was in 1986, and it is projected to return in 2061.

• The comet is named after English astronomer Edmond Halley, who examined reports of a comet approaching Earth in 1531, 1607 and 1682. He concluded that these three comets were actually the same comet returning over and over again, and predicted the comet would come again in 1758.

HISTORY OF HALLEY’S COMET

• The first known observation of Halley's took place in 239 B.C., according to the European Space Agency. Chinese astronomers recorded its passage in the Shih Chi and Wen Hsien Thung Khao chronicles.

• When Halley's returned in 164 B.C. and 87 B.C., it probably was noted in Babylonian records now housed at the British Museum in London. "These texts have important bearing on the orbital motion of the comet in the ancient past," noted a Nature Research Paper about the tablets.

• Halley's most famous appearance occurred shortly before the 1066 invasion of England by William the Conqueror. It is said that William felt the comet heralded his success. In any case, the comet was put on the Bayeux Tapestry – which chronicles the invasion – in William's honour.

• This portion of the Bayeux Tapestry shows Halley's Comet during its appearance in 1066. 

Halley’s in History

• Another appearance of the comet in 1301 possibly inspired Italian painter Giotto's rendering of the Star of Bethlehem in "The Adoration of the Magi,"according to the Britannica encyclopedia.

• Astronomers in these times, however, saw each appearance of Halley's Comet as an isolated event. Comets were often foreseen as a sign of great disaster or change.

Facts about Halley’s Comet

• Halley's Comet is named after the astronomer Edmund Halley (1656 - 1742). Although the comet is named afer him, he didn't actually discover it. Instead, he believed that a comet that he observed in 1682 could be the same comet that had been observed in 1607 and 1531. He believed that comets actually orbit the Sun just like planets and that the comet he had seen would return in about 76 years later if it was to follow the same pattern. It returned in 1758 as he predicted. Although he had died by the time this happened, the comet became known as Halley's Comet.

Facts about Halley’s Comet

• Halley's Comet is darker than coal, and reflects only 4% of the sunlight it receives. It only shines brightly when it is close enough to the Sun for its dust and vapours to be burnt off.

• Halley's Comet is shaped like a peanut and is about 15 kilometres (9 miles) long, and 8 kilometres (5 miles) wide and thick.

CARACOL TEMPLE

• Caracol is an important Mayan city that flourished in the 6th century AD and now lies in ruins in west-central Belize, near the border with Guatemala

• The city, which lay hidden in the jungle until its discovery in 1938, contains numerous pyramids, royal tombs, dwellings and other structures, as well as a large collection of Mayan art.

• El Caracol means winding staircase or snail. This building is dated 600 AD to 850 AD.

• The Tower is 48 feet high with many windows which allowed for observing the equinoxes and summer solstice.

• Caracol Temple was also aligned with the appearance of celestial bodies such as the Pleiades and Venus.

New grange

• Located in Ireland• New grange is best known

for the illumination of its passage and chamber by the winter solstice

• Underground chamber with passageways which point to the rising sun at winter solstice

• Window allows light to enter at sunrise on the first day of winter.

• Its purpose is to allow sunlight to penetrate the chamber on the shortest days of the year, around December 21st, the winter solstice. 

• At dawn, from December 19th to 23rd, a narrow beam of light penetrates the roof-box and reaches the floor of the chamber, gradually extending to the rear of the chamber.

• Originally used as calendar