Friday, August 25, 2006

Sun with satellite

Launched on Dec. 2, 2005, SOHO observes the sun's deep interior and also its interactions all the way out to Earth's orbit and beyond, where the magnetized solar wind of atomic particles sweeps through interplanetary space.


Carrying the Expedition 12 crew, a Soyuz TMA-7 that launched from the Baikinour Cosmodrome in Kazakhstan approaches the International Space Station.

Image credit: NASA

More about comets

A comet is a minor planet made up of rock, dust and ice. It originates from a cloud of debris remaining from the condensation of the solar nebula. Comets are unique because they are created in the outer solar system, and are greatly affected by the planets they pass. While a comet is orbiting, its path is constantly being altered as it nears surrounding planets. These changes in orbit can send it on a path approaching the sun, where it will burn up, or can be cast completely out of the solar system.
The tail of a comet is actually called the coma, which is composed of gas and dust streams. When a comet passes through the inner solar system, the sun lights up these streams so that we are able to see it. This is how we have been able to see Halley’s Comet from Earth.
The orbital periods of comets vary, but have been divided into three categories: Short period comets; long period comets; and Single-apparition comets. While Short period comets orbit for 200 years or less, long period comets are bound by gravity to the sun, and remain much longer. Single-apparition comets have unusual orbits and are thrown out of the solar system forever.

What are black holes

The anomalous black holes are concentrated areas of mass so immense, that the mammoth force of gravity denies anything within a certain area around it from passing. This area is called the event horizon of a black hole.
We have given black holes their name because light inside the event horizon can never be seen by mankind, or any outside observer. We believe that black holes in space are created by the collapse of a red super giant star. As these stars reach the end of their lives, an imbalance of inward and outward pressure forces the star to collapse.
Information on black holes is limited, though numerous schools of theory exist. We know black holes exist not because we can see them, but because of the impact they have on the space around them.
Scientists like Karl Schwarzschild, Jayant Narlikar and Stephen Hawking have built upon ideas from Einstein and others to offer theories on black holes. And yet, they remain an enigma. Because extensive, proven black holes information is scarce, they remain a constant area of intrigue and curiosity.

Something more about our solar system

The solar system is the home to the sun, nine planets including the Earth, the 158 known moons that orbit those planets, as well as a countless number of other celestial bodies that exist throughout this vast space. Such celestial bodies include things like asteroids, meteoroids and comets.
Though the events leading up to the formation of the solar system are still being debated, is it believed to be more than 4.6 billion years old!
The word "solar" is derived from the Latin word for sun, Sol, leading to the term solar system, or the system of the sun. The planets that orbit the sun within the solar system include Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and the smallest planet of Pluto. Jupiter is by far the largest with an overall mass of more than three times that of the Earth. The sun itself makes up an estimated 99.86% of the solar system’s total mass.

From 9 to 12

Image: The 12 planets under the newly proposed IAU definition. Planet sizes are shown to scale but their orbital distances are not to scale. Credit: IAU/Martin Kornmesser

According to new definition proposed by the International Astronomical Union (IAU) we now have 12 planets in our solar system.
* The asteroid Ceres, which is round, would be recast as a dwarf planet in the new scheme
* Pluto would remain a planet. It's moon Charon would become planet, and both would be called "plutons"
* A Pluto sized object, 2003 UB313 would also be called a pluton

The discoverer of the 12th planet, Mike Brown, thinks that idea of 12 planets is "lousy". He also says that accourding to the new definition there are already 53 planets in our solar system, and much more to be discovered.

The definition says that all round objects orbiting stars will be called planets.
"A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet."

Image: In proposing a new planet definition, the International Astronomical Union put 12 objects on a watch list of candidates that need further study. They are shown here to scale with Earth. Credit: IAU/Martin Kornmesser

Sunday, August 13, 2006

Universe could be larger

Astronomers recently calculated the distance to the relatively nearby galaxy M33 (The Triangulum Galaxy) as being about 15% further than previously estimated. They analyzed the distance using several telescopes, fine tuning their instruments very carefully. This measurement means that the Hubble constant - which astronomers use to measure distances in the Universe - could be off as well. The Universe might actually be 15% larger than previously believed.
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