Scientists investigating a large crater in a field in northern Latvia, believed to have been caused by a meteorite, now suspect it was a hoax.

The Latvian media reported on the fall of the meteorite near the city Mazsalaca Valmiera District. In the area of the fall of the meteorite crater width 20 and depth of 10 meters.

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The night sky will sparkle with “falling stars” on Tuesday and Wednesday as Earth passes through a trail of dusty debris from the Swift-Tuttle Comet, say scientists.

The light show, called the Perseid meteor shower, kicks off each year in late-July and increases in intensity, peaking a couple of weeks later.

On a clear night in a dark sky “you should see dozens of meteors per hour,” notes Bill Cooke of NASA’s Meteoroid Environment Office.

East Asia is best placed to see the shower at its most intense moment, which is predicted for 1800 GMT on August 12, according to the US publication Sky and Telescope (http://skyandtelescope.com/).

The meteors are also active for many days before and after this date, though the light reflected by a waning quarter moon may obstruct the view somewhat.

The Perseids occur when Earth runs into a trail of dust and pebbles deposited by the comet Swift-Tuttle in its 130-year orbit around the Sun.

This debris strikes the upper atmosphere at around 60 kilometers (37 miles) per second, a speed that causes it to burn up into a white-hot streaks. Bigger chunks can be seen as fireballs.

Meteor showers vary from year to year, depending on the amount of debris.

In the early 1990s, there were several spectacular Perseid shows, with bursts of several hundred meteors per hour.

Meteors are named after the constellation from which they seem to appear — in this case, Perseus, a northern constellation lying east of Cassiopeia and north of Taurus.

(Agencies)

source: http://sina.com/

Many of the primitive bodies wandering the asteroid belt between Mars and Jupiter are former comets, tossed out of orbit by a brutal ballet between the giant outer planets, say a team of astrophysicists.

A commonly accepted theory is that the asteroid belt is the rubble left over from a “proto-planetary disk,” the dense ring of gas that surrounds a new-born star.

But the orbiting rocks have long been a source of deep curiosity. They are remarkably varied, ranging from mixtures of ice and rock to igneous rocks, which implies they have jumbled origins.

The answer to the mystery, according to a study published by the British journal Nature , is that a “significant fraction” of the asteroid population in fact comprises ex-comets.

Famously described as “dirty snowballs” of ice and dust, comets are lonely, long-distance wanderers of the Solar System whose elliptical swing around the Sun can take decades.

Researchers in France and the United States ran a mathematical model of the development of the early Solar System, when the planets were accreting from clustering masses of dust and gas.

According to this model, the nascent giant planets — Jupiter, Saturn, Uranus and Neptune — orbited at this time in a pretty compact configuration, between five and 15 astronomical units (AUs) from the Sun.

An AU is a standard unit of measurement for Solar System distances. It equals the distance from the Earth to the Sun, or around 150 million kilometres (93 million miles).

Beyond the giant planets was a disk-shaped mass of comets, known as trans-Neptunian objects, between 16 and 30 AUs from the Sun.

As the giants became bigger and bigger, their orbits became unstable.

Eventually, after around 600 million years, Uranus and Neptune were kicked out by gravitational jousting.

They rammed into the disk of comets and scattered its members throughout the Solar System, according to this model. Many of them were captured by the weak gravitational force of the asteroid belt, where they remain to this day.

“It’s a paradigm shift,” said Matthieu Gounelle of France’s National Centre for Scientific Research (CNRS) in a press release.

“The asteroid belt is not just a leftover from the formation of the Solar System, but also that of violent phenomena” including the great planetary migration.

If the model is right, it implies that the difference between the most primitive asteroids and comets is even slimmer than thought.

It would also shed light on the controversial origin of micrometeorites, or tiny extraterrestrial particles that survive the fiery passage through Earth’s atmosphere.

Micrometeorites are different from meteorites in composition and texture, and this could be explained if they derive from comets, which are richer in organic material and crumblier than native asteroids.

(Agencies)

source: http://sina.com/

A black hole is an object with such a powerful gravitational field that it absorbs all the light that passes near it and reflects nothing.

Until now, identified black holes have been either super-massive (several million to several billion times the mass of the Sun) in the centre of galaxies, or about the size of a typical star (between three and 20 Solar masses).

Now, an international team has discovered the black hole HLX-1, 290 million light years from Earth, which it is more than 500 times the mass of the Sun, using the European Space Agency’s telescope.

Team member Dr Sean Farrell of the University of Leicester said: “While it is widely accepted that stellar mass black holes are created during death throes of massive stars, it is still unknown how super-massive black holes are formed.

“One theory is that super-massive black holes may be formed by the merger of a number of intermediate mass black holes. To ratify such a theory, however, you must first prove the existence of intermediate black holes.

“The identification of HLX-1 is therefore an important step towards a better understanding of the formation of the super-massive black holes that exist at the centre of the Milky Way and other galaxies.”

In fact, the HLX-1 (Hyper-Luminous X-ray source 1) lies towards the edge of the galaxy ESO 243-49. It is ultra- luminous in X-rays, with a maximum X-ray brightness of approximately 260 million times that of the Sun.

The X-ray signature of HLX-1 and the lack of a counterpart in optical images confirm that it is neither a foreground star nor a background galaxy, and its position indicates that it is not the central engine of that galaxy.

And, using XMM-Newton observations carried out on the 23rd November 2004 and the 28th November 2008, the team showed that HLX-1 displayed a variation in its X-ray signature. This indicated that it must be a single object and not a group of many fainter sources.

The huge radiance observed can only be explained if HLX-1 contains a black hole more than 500 times the mass of the Sun. No other physical explanation can account for the data.

source: http://www.discoveryon.info/