HOW BIG IS bRHmH's aakaaSh........
Posted by Vishva News Reporter on January 4, 2002

From: Guinness World Record: Natural World: Universe

Nearest Black Hole
The closest black hole is only 1,600 light years (=9385 trillion miles with 1 light year = 5.83 trillion miles) from Earth and is known as V4641 Sgr and located in milky way.. It was discovered in January 2000 by astronomers at Massachusetts Institute of Technology and the National Science Foundation's National Radio Astronomy Observatory. Unlike normal black holes, which weigh several times the mass of the Sun, super-massive black holes (pictured on the Guinness Web Site) reside in the hearts of galaxies and can be as massive as several hundred million times that of the Sun. A black hole is an area of space made up of extremely dense matter in which everything is pulled in and nothing can escape, not even light. They are spherical in shape and, like planets and stars, have a gravitational field. The escape velocity of a black hole's gravitational field is greater or equal to the speed of light. Black holes are formed when massive stars die in a titanic explosion called a "supernova".

Largest Galaxy
The central galaxy of the Abell 2029 galaxy cluster, 1070 million light years(6276 trillion miles ) distant in Virgo, has a major diameter of 5,600,000 light years (328 million trillion miles) - 80 times the diameter of our own Milky Way galaxy (pictured on the Guinness Web Site)

Farthest Object Visible By The Naked Eye
The remotest heavenly body visible with the naked eye is the Great Galaxy in the constellation of Andromeda. A silver smudge in the sky gives the Andromeda Galaxy away - at a mind-boggling 2,200,000 light years (12.9 million trillion miles) from Earth, anyone can spot it! One of the closest galaxies to our own, the light we see is the result of 200,000,000,000 stars shining together. The spiral galaxy is said to have been discovered by German astronomer, Simon Marius, around 1611.

Coldest Place In The Universe
The Boomerang Nebula is a cosmic refrigerator with a mind-numbing temperature of -272C (-521.6F). Pack your thermals - it's officially the coldest place in the universe! The freezing cold spot is made from a dust and gas cloud thrown off by a dying star, which astronomers call a "white dwarf". It's so cold because the center of the Nebula is forced to expand further and faster, as the dying planet sheds more and more cosmic junk. Deep space decay, however, also leads to cosmic regeneration. The dust and gas thrown out at the center of the nebula will eventually collect and merge to form new planets and solar systems like our own (pictured on the Guinness Web Site).

Nearest Star (Excluding The Sun)
Excepting the special case of our own Sun, the nearest star to Earth is the very faint Proxima Centauri, discovered in 1915, which is 4.23 light years (24.8 trillion miles) away. Proxima Centauri is also called Alpha Centauri C. The star cannot be seen without a telescope.

Compare the nearest start to our own sun which is 93.5 million miles away from our planet Earth....learn more about our own sun which sustains our life by clicking on the next line.....


From Arizona Edu Web Site


The Sun is a normal G2 star, one of more than 100 billion stars in our galaxy.

        diameter:    1,390,000 km.
        mass:        1.989e30 kg
        temperature: 5800 K (surface)
                     15,600,000 K (core)

   The Sun is by far the largest object in the solar system. It contains more than 99.8% of the total mass of the Solar System (Jupiter contains most of the rest).

   It is often said that the Sun is an "ordinary" star. That's true in the sense that there are many others similar to it. But there are many more smaller stars than larger ones; the Sun is in the top 10% by mass. The median size of stars in our galaxy is probably less than half the mass of the Sun.

   The Sun is personified in many mythologies: the Greeks called it Helios and the Romans called it Sol.

   The Sun is, at present, about 75% hydrogen and 25% helium by mass (92.1% hydrogen and 7.8% helium by number of atoms); everything else ("metals") amounts to only 0.1%. This changes slowly over time as the Sun converts hydrogen to helium in its core.

   The outer layers of the Sun exhibit differential rotation: at the equator the surface rotates once every 25.4 days; near the poles it's as much as 36 days. This odd behavior is due to the fact that the Sun is not a solid body like the Earth. Similar effects are seen in the gas planets. The differential rotation extends considerably down into the interior of the Sun but the core of the Sun rotates as a solid body.

   Conditions at the Sun's core (approximately the inner 25% of its radius) are extreme. The temperature is 15.6 million Kelvin and the pressure is 250 billion atmospheres. At the center of the core the Sun's density is more than 150 times that of water.

   The Sun's energy output (3.86e33 ergs/second or 386 billion billion megawatts) is produced by nuclear fusion reactions. Each second about 700,000,000 tons of hydrogen are converted to about 695,000,000 tons of helium and 5,000,000 tons (=3.86e33 ergs) of energy in the form of gamma rays. As it travels out toward the surface, the energy is continuously absorbed and re-emitted at lower and lower temperatures so that by the time it reaches the surface, it is primarily visible light. For the last 20% of the way to the surface the energy is carried more by convection than by radiation.

   The surface of the Sun, called the photosphere, is at a temperature of about 5800 K. Sunspots are "cool" regions, only 3800 K (they look dark only by comparison with the surrounding regions). Sunspots can be very large, as much as 50,000 km in diameter. Sunspots are caused by complicated and not very well understood interactions with the Sun's magnetic field.

   A small region known as the chromosphere lies above the photosphere.

   The highly rarefied region above the chromosphere, called the corona, extends millions of kilometers into space but is visible only during eclipses (left). Temperatures in the corona are over 1,000,000 K.

   The Sun's magnetic field is very strong (by terrestrial standards) and very complicated. Its magnetosphere (also known as the heliosphere) extends well beyond Pluto.

   In addition to heat and light, the Sun also emits a low density stream of charged particles (mostly electrons and protons) known as the solar wind which propagates throughout the solar system at about 450 km/sec. The solar wind and the much higher energy particles ejected by solar flares can have dramatic effects on the Earth ranging from power line surges to radio interference to the beautiful aurora borealis.

   Recent data from the spacecraft Ulysses show that during the minimum of the solar cycle the solar wind emanating from the polar regions flows at nearly double the rate, 750 kilometers per second, that it does at lower latitudes. The composition of the solar wind also appears to differ in the polar regions. During the solar maximum, however, the solar wind moves at an intermediate speed.

   Further study of the solar wind will be done by the recently launched Wind, ACE and SOHO spacecraft from the dynamically stable vantage point directly between the Earth and the Sun about 1.6 million km from Earth.

   The solar wind has large effects on the tails of comets and even has measurable effects on the trajectories of spacecraft.

   Spectacular loops and prominences are often visible on the Sun's limb (left).

   The Sun's output is not entirely constant. Nor is the amount of sunspot activity. There was a period of very low sunspot activity in the latter half of the 17th century called the Maunder Minimum. It coincides with an abnormally cold period in northern Europe sometimes known as the Little Ice Age. Since the formation of the solar system the Sun's output has increased by about 40%.

   The Sun is about 4.5 billion years old. Since its birth it has used up about half of the hydrogen in its core. It will continue to radiate "peacefully" for another 5 billion years or so (although its luminosity will approximately double in that time). But eventually it will run out of hydrogen fuel. It will then be forced into radical changes which, though commonplace by stellar standards, will result in the total destruction of the Earth (and probably the creation of a planetary nebula).

The Sun's satellites

There are nine planets and a large number of smaller objects orbiting the Sun. (Exactly which bodies should be classified as planets and which as "smaller objects" has been the source of some controversy, but in the end it is really only a matter of definition.)


            Distance  Radius    Mass
Planet      (000 km)   (km)     (kg)   Discoverer   Date
---------  ---------  ------  -------  ----------  -----
Mercury       57,910    2439  3.30e23
Venus        108,200    6052  4.87e24
Earth        149,600    6378  5.98e24
Mars         227,940    3397  6.42e23
Jupiter      778,330   71492  1.90e27
Saturn     1,426,940   60268  5.69e26
Uranus     2,870,990   25559  8.69e25   Herschel    1781
Neptune    4,497,070   24764  1.02e26   Galle       1846
Pluto      5,913,520    1160  1.31e22   Tombaugh    1930

More detailed data and definitions of terms can be found on the data page.


More about the Sun

Open Issues

  • Is there a causal connection between the Maunder Minimum and the Little Ice Age or was it just a coincidence? How does the variability of the Sun affect the Earth's climate?
  • Several careful experiments have failed to detect the expected flux of neutrinos from the Sun. The explanation will probably turn out to be just a minor glitch in some esoteric calculation. But that's what they said in 1900 about the orbit of Mercury.
  • Since all the planets except Pluto orbit the Sun within a few degrees of the plane of the Sun's equator, we know very little about the interplanetary environment outside that plane. The Ulysses mission will provide information about the polar regions of the Sun.
  • The corona is much hotter than the photosphere. Why?

Contents ... Overview ... Sun ... Mercury ... Spacecraft ... Data Host

Bill Arnett; last updated: 2002 May 01



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