Astronomy Blog

They look like the work of abstract artists, but the images reflect reality – the rhythmic shapes of mountains, deserts, clouds, fjords, scattered cities and towns turned into brilliant patches of red, green and blue – flashed to earth from a satellite 440 miles in space.

More than three dozen of 400,000 photos taken by Landsat-7 since it was launched in 1999 are on display in an exhibit at the Library of Congress called “Earth as Art.”

Images from Landsat-7 are mainly used by the U.S. Geological Survey to keep tabs on crops and minerals. Some have been used by scientists to locate promising spots to dig for dinosaur bones in the Gobi desert. Read the rest of this entry »

Earth is the third planet from the Sun and is the largest of the terrestrial planets in the Solar System, in both diameter and mass. Home to myriad species including humans, it is also referred to as “the Earth”, “Planet Earth”, “Gaia”, “Terra”, and “the World”.

The Earth is the first planet known to have liquid water on the surface and is the only place in the universe known to harbor life. Earth has a magnetic field that, together with a primarily nitrogen-oxygen atmosphere, protects the surface from radiation that is harmful to life. The atmosphere also serves as a shield that causes smaller meteors to burn up before they strike the surface. Read the rest of this entry »

Mercury is the innermost and smallest planet in the solar system, orbiting the Sun once every 88 days. It ranges in brightness from about -2.0 to 5.5 in apparent magnitude, but is not easily seen as its greatest angular separation from the Sun (greatest elongation) is only 28.3°. It can only be seen in morning or evening twilight. Comparatively little is known about the planet: the only spacecraft to approach Mercury was Mariner 10 from 1974 to 1975, which mapped only 40%-45% of the planet№s surface. The period of rotation is 58.6462 days.

Physically, Mercury is similar in appearance to the Moon as it is heavily cratered. It has no natural satellites and no atmosphere. The planet has a large iron core which generates a magnetic field about 1% as strong as that of the Earth. Surface temperatures on Mercury range from about 90 to 700 K, with the subsolar point being the hottest and the bottoms of craters near the poles being the coldest. Read the rest of this entry »

Mars is the fourth planet from the Sun in the solar system. It is named after Mars, the god of war in Roman mythology (the counterpart to Ares, the god of war in Greek mythology) because of its red color as viewed in the night sky. This feature also earned it the name of “the Red Planet.” Mars has two moons (Phobos and Deimos) which are both small and oddly-shaped, possibly being captured asteroids. The prefix areo- refers to Mars.

Mars has certainly been seen by skygazers since prehistoric times. It was known by the Egyptians as “Her Deschel” or “the Red One.” Among the Babylonians Mars was known as “Nirgal” or “the Star of Death”. The Romans were the ones to give Mars its modern name, after the God of War. Mythology and Metaphysics Read the rest of this entry »

Jupiter is the fifth planet from the Sun and by far the largest within our solar system; some have described the solar system as consisting of the Sun, Jupiter, and assorted debris. It and the other gas giants Saturn, Uranus, and Neptune are sometimes referred to as “Jovian planets.” The Romans named the planet after the Roman god Jupiter. The astronomical symbol for the planet is a stylized representation of the god’s lightning bolt. The Chinese, Korean, and Japanese cultures refer to the planet as the Wood Star, based on the Five Elements.

Overview

Jupiter has been known since ancient times and is visible to the naked eye in the night sky. In 1610, Galileo Galilei discovered the four largest moons of Jupiter using a telescope, the first observation of moons other than Earth’s. Read the rest of this entry »