Sunday, June 11, 2006

Right start in astronomy

Too many newcomers to astronomy get lost in dead ends and quit in frustration. It shouldn't be that way. Alan M. MacRobert at explains how simple, easy and interesting can astornomy be! You just have to start right.

Some of the tips are:

1. Learn the sky with the unaided eye.
2. Ransack your public library.
3. Thinking telescope? Start with binoculars.
4. Dive into maps and guidebooks.
5. Keep an astronomy diary.
6. Seek out other amateurs.
7. When it's time for a telescope, plunge in deep.
8. Lose your ego.
9. Relax and have fun.

For more details visit skyandtelescope

Thursday, June 08, 2006

Our solar system

Our solar system is part of the Milky Way galaxy, a spiral galaxy with a diameter of about 100,000 light years containing about 200 billion stars. The solar system comprises our Sun and the retinue of celestial objects gravitationally bound to it. Traditionally, this is said to consist of the Sun, nine planets and their 158 currently known moons; however, a large number of other objects, including asteroids, meteoroids, planetoids, comets, and interplanetary dust, orbit the Sun as well. The Sun is a main sequence G2 star that contains 99.86% of the system's known mass. The point at which solar system ends and interstellar space begins is not precisely defined, since its outer boundaries are delineated by two separate forces: the solar wind and the Sun's gravity.

The current hypothesis of solar system formation is the nebular hypothesis, first proposed in 1755 by Immanuel Kant and independently formulated by Pierre-Simon Laplace. It states the solar system was formed from a gaseous cloud called the solar nebula. It had a diameter of 100 AU and was 2-3 times the mass of the Sun. Over time, a disturbance, possibly a nearby supernova, sent shock waves into space, which squeezed the nebula, pushing more and more of its matter inward until gravitational forces overcame its internal gas pressure and it began to collapse. As the nebula collapsed, it decreased in size, which in turn caused it to spin faster to conserve angular momentum. And as the competing forces associated with gravity, gas pressure, magnetic fields, and rotation acted on it, the contracting nebula began to flatten into a spinning pancake shape with a bulge at the center.

When the nebula further condensed, a protostar was formed in the middle. This system was heated by friction of the rocks colliding into each other. Lighter elements such as hydrogen and helium evaporated out of the centre and migrated to the disc's edges, thus concentrating heavier elements to form dust and rocks in the centre. These heavier elements clumped together to form planetesimals and protoplanets. In the outer regions of this solar nebula, ice and volatile gases were able to survive, and as a result, inner planets are rocky and the massive outer planets captured large amounts of lighter gases, such as hydrogen and helium.

After 100 million years, the pressures and densities of hydrogen in the centre of the collapsed nebula became great enough for the protosun to sustain thermonuclear fusion reactions. As a result of this, hydrogen was converted to helium, and a great amount of heat was released.

During that time, the protostar turned into the Sun and the protoplanets and planetesimals were transformed into planets. All of the planets formed in a relatively short time of a few million years.

Scientists estimate that the solar system is 4.6 billion years old. To calculate this figure, they examine an unstable element, which is subject to radioactive decay. By observing how much this element has decayed, they can calculate how old this element is. The oldest rocks on earth are approximately 3.9 billion years old, however it is hard to find these rocks as the earth has been thoroughly resurfaced. To estimate the age of the solar system, scientists must find rocks from space, such as meteorites – which are formed during the early condensation of the solar nebula. The oldest meteorite was found to have an age of 4.6 billion years, hence the solar system must be at least 4.6 billion years old.

Titan on the side

Titan is the largest Saturn's moon, it peaks out from under the planet's rings of ice
This view looks toward Titan (5,150 kilometers, or 3,200 miles across) from slightly beneath the ringplane. The dark Encke gap (325 kilometers, or 200 miles wide) is visible here, as is the narrow F ring.
Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were taken with the Cassini spacecraft narrow-angle camera on April 28, 2006 at a distance of approximately 1.8 million kilometers (1.1 million miles) from Titan.

Image credit: NASA/JPL/Space Science Institute


This time exposure photograph of the Mobile Service Structure makes the structure apprear as a streak of light as it moves away from the Skylab 4 space vehicle the night before the launch.
Skylab 4 launched on Nov. 16, 1973. The crew -- Commander Gerald Carr, Mission Pilot William Pogue and Edward Gibson -- spent 84 days aboard the station.

Image credit: NASA (Full Resolution)

SuitSat - new satellite

Using a simple police scanner or ham radio, you can listen to a disembodied spacesuit circling Earth.
One of the strangest satellites in the history of the space age was in orbit! The spacesuit is the satellite -- "SuitSat" for short.
SuitSat is a Russian brainstorm. Old spacesuits can be turned into useful satellites. SuitSat is a first test of that idea.

Photo: ISS astronaut Mike Finke spacewalks in a Russian Orlan spacesuit in 2004. SuitSat will have no one inside.

Spacesuit was equipped with three batteries, a radio transmitter and internal sensors to measure temperature and battery power. As SuitSat circled Earth, it transmited its condition to the ground.
SuitSat could be heard by anyone on the ground. All you need is an antenna and a radio receiver that you can tune to 145.990 MHz FM. A police band scanner or a hand-talkie ham radio would work just fine. Students, scouts, teachers and ham radio operators were able to tune in.
Using Science@NASA’s J-PASS utility you could find out when will SuitSat orbit over your city. All you need to enter is you zip code.

Photo: Tune your FM radio to 145.990 MHz.

When you point antena you could hear:
SuitSat transmits for 30 seconds, pauses for 30 seconds, and then repeats. "This is SuitSat-1, RS0RS”
Suitsat 'talked' using a voice synthesizer. It's pretty amazing.

Monday, June 05, 2006

Huge storms on Jupiter

Two biggest storms in solar system are about to happened!

Storm #1 is the Great Red Spot, twice as wide as Earth itself, with winds blowing 350 mph. The behemoth has been spinning around Jupiter for hundreds of years.

Storm #2 is Oval BA, also known as "Red Jr.," a youngster of a storm only six years old. Compared to the Great Red Spot, Red Jr. is half-sized, able to swallow Earth merely once, but it blows just as hard as its older cousin.

Photo: Jupiter's two red spots

Amy Simon-Miller of the Goddard Space Flight Center said that closest approach is going to be on the 4th of July. Two storms are converging. Amy Simon-Miller is monitoring the storms using the Hubble Space Telescope. "The Great Red Spot is not going to 'eat' Oval BA or anything like that." But the storms' outer bands will pass quite close to one another—and no one knows exactly what will happen.

Photo: Red Oval BA

The color of the Great Red Spot itself is a mystery. A popular theory holds that the storm dredges up material from deep inside Jupiter's atmosphere, lifting it above the highest clouds where solar ultraviolet rays turn "chromophores" (color-changing compounds) red. A beefed-up Oval BA could suddenly do the same.

Some amateur astronomers are already monitoring this event

Sunday, June 04, 2006

Stars and Planets Alignment

Mark you calendar: June 7th, June 15th and June 17th. Three sunsets, three planets and a star cluster – good way to end the day.
Something remarkable is about to happen in the evening sky. Three planets and a star cluster are converging for a close encounter you won't want to miss.

June 7th: If you are Star Trek fan, make the Vulcan "Live Long and Prosper" sign with your right hand. Hold it at arm's length. By Wednesday, June 7th, both Mars and Saturn will fit inside the "V"

June 15th: This is special night. Mars will pass directly in front of the Beehive. See this with binoculars or with small telescope. Red Mars is 16 times brighter than the surrounding stars. It’ll look like a red supernova has gone off inside the cluster.
More in June 15th, Mercury leaps out of the glare of the Sun, soaring into the evening sky not far from Saturn and Mars. Mercury is easy to see even from over-lit cities.

June 17th: Mars and Saturn draw so close together you might think they are going to collide (of course they won’t). Stick out your pinky and hold it at arm's length. The two planets will fit behind the tip with room to spare. Mercury, meanwhile, hovers just below.

Saturday, June 03, 2006

New Moons of Pluto

Astronomers using NASA’s Hubble Space Telescope discover that Pluto, the ninth planet is our solar system, may have not one, but three moons.

Picture: An artist's concept of the Pluto system as seen from the surface of one of the candidate moons.

Pluto was discovered in 1930. It is 3 billion miles away form sun in the heart of the Kupiter Belt, a vast region of icy, rocky bodies beyond Neptune’s orbit. Charon, Pluto’s moon, was discovered in 1978.
"If, as our new Hubble images indicate, Pluto has not one, but two or three moons, it will become the first body in the Kuiper Belt known to have more than one satellite," said Hal Weaver of the Johns Hopkins Applied Physics Laboratory, Laurel, Md. He is co-leader of the team that made the discovery.
New moons are 44,000 km away from Pluto, and that is two or three times more far than Pluto – Charon
These are tiny moons. Their estimated diameters lie between 64 and 200 kilometers. Charon, for comparison, is about 1170 km wide, while Pluto itself has a diameter of about 2270 km.
Two new moon candidate are seen with Hubble on May 15, 2005. Three days later, Hubble looked at Pluto again. The two objects were still there and appeared to be moving in orbit around Pluto
The team look for any other moons around Pluto but didn’t find nothing.

Picture: Hubble Space Telescope images taken in May 2005 show the candidate moons apparently rotating counterclockwise around Pluto.
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