Tag Archives: Astronomy

Ancient Astronomy

The Night Sky

Evidence indicates that people were interested in observing and understanding the sky and the celestial objects thousands of years ago. For example, the 4000 year old Stonehenge, in southern England was believed to be built to predict the positions of the sun and the moon.

Written records of astronomical observations left by the ancient Babylonians, Egyptians and the Chinese exist today. During 1300’s B.C., Chinese astronomers mapped the positions of the stars and recorded the eclipses. By about 700 B.C., the Babylonians were predicting when the planets would appear closest and farthest from the sun. The ancient Egyptians determined the beginning of springtime by the position of the brightest star in the sky, the Sirius.

Pythagoras, a Greek philosopher and scientist who lived about 500 B.C., reasoned that the earth was round. During the A.D, 100’s Claudius Ptolemy, a Greek astronomer who lived in Alexandria, Egypt published a work called the Almagest promoting the idea that the planets, the sun, moon and the stars all revolved around the earth.

Astronomers accepted Ptolemy’s geocentric (earth-centered) theory for over 1500 years until Nicolaus Copernicus’s revolutionary heliocentric (sun-centered) theory, that the earth and the other planets revolved around the sun, took hold. So began the Modern Astronomy.

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The Hubble Space Telescope – Our Eyes Into the Unknown

Hubble Space Telescope

Thirty years ago, NASA launched one of the greatest pieces of discovery equipment into space to get a deeper understanding of the unknown world that exists outside of our own.

On April 24, 1990, the Hubble Space Telescope was placed on the Discovery space shuttle and was launched into low Earth orbit about 340 miles above, where it functions to this day. The telescope was the creation of a joint venture between NASA and the European Space Agency. Named after the astronomer, Edwin Hubble, the telescope was not the first of its kind but is one that has proven itself with some of the greatest discoveries made in space and time.

The Hubble Space Telescope was built to see cosmic creations that could only be imagined by the most obscure minds of science and philosophy. The powerful and clear images created by the telescope have helped researchers see into black holes, discover new planets, and witness the creation of stars. The telescope achieves this with a 7.9 ft mirror and four internal mechanisms that view in ultraviolet, visible, and near-infrared sectors on the electromagnetic spectrum.

The Hubble Space Telescope is unique in one sense. It is the only telescope that is built to be repaired, serviced, and upgraded by astronauts in space. It is because of this that the telescope has been able to stay in service for so long, with no plans of stopping. The last servicing mission took place in 2009, where the team placed a Soft Capture Mechanism onto the telescope to allow a robotic spacecraft to be attached to it in the future. The next servicing mission is planned for 2024.

One of Hubble’s main missions was to determine the size and age of the universe. While the size of the universe remains infinite, scientists were able to gather data from the Hubble Space Telescope to figure out that the universe is a significant 13.7 billion years old.

NASA credits the telescope for countless discoveries of moons, stars, and black holes. They say that the telescope is working better today than it ever did before; they intend to continue on that path for many years to come.

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A Look into Telescope

The telescope is an optical instrument used to observe objects that are a significant distance away, especially those that are not seen directly by the naked human eye. It is a collection of lenses and/or mirrors that allows the user to see objects that are far away, by either increasing the brightness around the object or by magnifying the object. The telescopes are able to perform at different levels of the electromagnetic spectrum from the radio waves to gamma rays.

The first optical telescope, according to some sources, was made by the Dutch lens-grinder names Hand Lippershey in the year 1608. Around the same time Galileo developed the first ever astronomical telescope. It was a tube that contained two lenses of different focal length that had been aligned on one axis.

Using this telescope, and the different versions that followed after, Galileo performed the first telescopic observation of the sky. During this time he discovered the lunar mountains, Jupiter’s four moons, sunspots, and the stars of the Milky Way.

There are two basic types of telescopes: the refracting telescope and the reflecting telescope.

The refracting telescope uses two lenses to work the light to focus on the object which tends to appear bigger than it really is. Both the lenses are convex lenses which work by bending the light inwards. The biggest refracting telescope in the world is present in the Yerkes Observatory of the University of Chicago.

The reflecting telescopes do not use lenses. They use mirrors to focus the light on the object and then they reflect the image back to the user.

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