CONSTELLATIONS..

BLACK HOLES

Care to make a black hole? these astrophycists are happy to share. it looks like in a sci-fi movies

IRON KILLS STARS

Why does the element iron kill stars? a very interesting facts that we don't usually heard. again from space.com. :p

A MUST SEE

A very fascinating objects in the night sky. this video is from www.space.com

A Space World Slideshow

A Space World Slideshow: "TripAdvisor™ TripWow ★ A Space World Slideshow ★ to . Stunning free travel slideshows on TripAdvisor"

CLICK THE HIGHLITED SENTENCE TO WATCH THE SLIDE SHOW.HOPE YOU SPACE EXPLORERS LIKE IT.:P

STARS...

History of Observations

Astronomy, the study of the heavens, may be the most ancient of the sciences, present since the dawn of recorded civilization, with the stars often playing a key role in religion and proving vital to navigation. The invention of the telescope and the discovery of the laws of motion and gravity in the 17th century prompted the realization that stars were just like the sun, all obeying the same laws of physics. In the 19th century, photography and spectroscopy — the study of the wavelengths of light that objects emit — made it possible to investigate the compositions and motions of stars from afar, leading to the development of astrophysics. In 1937, the first radio telescope was built, enabling astronomers to detect otherwise invisible radiation from stars. In 1990, the first space-based optical telescope, the Hubble Space Telescope, was launched, providing the deepest, most detailed visible-light view of the universe.

Star Naming Designations

Ancient cultures saw patterns in the heavens that resembled people, animals or common objects — constellations that came to represent figures from myth, such as Orion the Hunter, a hero in Greek mythology. Astronomers now often use constellations in the naming of stars, with the International Astronomical Union, the world authority for assigning names to celestial objects, officially recognizing 88 constellations that cover the entire sky. Usually, the brightest star in a constellation is has "alpha," the first letter of the Greek alphabet, as part of its scientific name. The second brightest star in a constellation is typically designated "beta," the third brightest "gamma," and so on until all the Greek letters are used, after which numerical designations follow.

Since there are so many stars in the universe, the IAU uses a different system for newfound stars. Most consist of an abbreviation that stands for either the type of star or a catalog that lists information about the star, followed by a group of symbols. For instance, PSR J1302-6350 is a pulsar, thus the PSR. The J reveals that a coordinate system known as J2000 is being used, while the 1302 and 6350 are coordinates similar to the latitude and longitude codes used on Earth.

A number of stars have possessed names since antiquity — Aldebaran, for instance, means "the follower" in Arabic, as it seems to follow the Pleiades, or Seven Sisters star cluster, across the sky. These possess scientific names as well — Aldebaran is also known as Alpha Tauri.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Characteristics

• Brightness

Astronomers describe star brightness in terms of magnitude and luminosity.— the brightest star in the night sky is Sirius, with an apparent magnitude of -1.46

• Color

Stars come in a range of colors, from reddish to yellowish to blue. The color of a star depends on surface temperature.

• Size

Astronomers generally measure the size of stars in terms of the radius of our sun. For instance, Alpha Centauri A has a radius of 1.05 solar radii (the plural of radius). Stars range in size from neutron stars, which can be only 12 miles (20 kilometers) wide, to supergiants roughly 1,000 times the diameter of the sun.

• Mass

Astronomers represent the mass of a star in terms of the solar mass, the mass of our sun. For instance, Alpha Centauri A is 1.08 solar masses.

Stars with similar masses might not be similar in size because they have different densities. For instance, Sirius B is roughly the same mass as the sun, but is 90,000 times as dense, and so is only a fiftieth its diameter.

THE SOLAR SYSTEM

At the heart of the solar system is our sun. The four planets nearest it are rocky, terrestrial worlds — Mercury, Venus, Earth and Mars. After that are four gas giants — Jupiter, Saturn, Uranus and Neptune. Between the orbits of Mars and Jupiter lies the asteroid belt, which includes the dwarf planet Ceres. Beyond the orbit of Neptune one finds the disk-shaped Kuiper belt, in which dwarf planet Pluto resides, and far beyond that is the giant, spherical Oort Cloud and the teardrop-shaped heliopause.

Discovery

For millennia, astronomers have followed points of light that seemed to move among the stars. The ancient Greeks named these planets, meaning wanderers. Mercury, Venus, Mars, Jupiter and Saturn were known in antiquity, and the invention of the telescope added the asteroid belt, Uranus and Neptune, Pluto and many of these worlds' moons. The dawn of the space age saw dozens of probes launched to explore our system, an adventure that continues today. The discovery of Eris kicked off a rash of new discoveries of dwarf planets, and more than 100 could remain to be found.

Inner Solar System

• Inner Planets

The inner four planets — Mercury, Venus, Earth and Mars — are made up mostly of iron and rock. They are known as terrestrial or earthlike planets because of their similar size and composition.

• Asteroid belt

Asteroids are minor planets, most of which circle the sun in a region known as the asteroid belt, between the orbits of Mars and Jupiter. Scientists estimate that there are more than 750,000 asteroids in the belt with diameters larger than three-fifths of a mile (1 kilometer), and there are millions of smaller asteroids. A number have orbits that take them closer into the solar system that sometimes lead them to collide with Earth or the other inner planets.

Outer Solar System

• Outer Planets

The outer planets are giant worlds with thick outer layers of gas. Nearly all their mass is made up of  hydrogen and helium, giving them compositions like that of the sun. Beneath these outer layers, they have no solid surfaces — the pressure from their thick atmospheres liquefy their insides, although they might have rocky cores. Rings of dust, rock, and ice encircle all these giants, with Saturn's being the most famous.

• Comets

Comets are often known as dirty snowballs, and consist mainly of ice and rock. When a comet's orbit takes it close to the sun, some of the ice in its central nucleus turns into gas that shoots out of the comet's sunlit side, which the solar wind carries outward to form into a long tail. Short-period comets that complete their orbits in less than 200 years are thought to originate from the the disk-shaped Kuiper belt, while long-period comets that take more than 200 years to return are thought to come from the spherical Oort cloud.

THE SUN

The sun is by far the largest object in our solar system, containing 99.8 percent of the solar system's mass. It sheds most of the heat and light that makes life possible on Earth and possibly elsewhere. Planets orbit the sun in oval-shaped paths called ellipses, and the sun is slightly off to the side of the center of each ellipse.