Earth under attack from Nemesis

Scientists have claimed that an invisible star which is supposed to be 5 times the size of Jupiter is kicking some deadly comets towards Earth.

They believe that the invisible which is nicknamed as " Nemesis" or " The DeathStar" could be responsible for mass extinction on Earth which occurs every 26 million years.

The stars spins through the galaxy and its gravitational pull drags a vast sphere of rock called Oort Cloud and dust twice as far as Nemesis. They are thrown towards Earth as comets which is causing destruction .

NASA scientists believe that they will be able to find about Nemesis using a new heat-seeking telescope that began scanning the skies in January. Researchers have come to know about the existence of Nemesis from orbit of a dwarf planet called Sedna.

The Wide-Field Infrared Survey Explorer which has found a thousand brown dwarf stars within 25 light years of the Sun has sent a photo of a comet disloged from the Oort Cloud.

Fastest moving planet

A small planet known as CoRoT-7b which is 500 light years from Earth and is the fastest moving planet known . It is moving around its star every 20.4 hours and is confirmed as a rocky planet.

CoRoT-7b is a rare breed of exoplanets with masses just a few times that of Earth.

Gigantic bubbles boiling on the surface of star Betelgeuse

Giant star Betelgeuse shed the equivalent mass of the Earth every year but how do it does is not properly understood. Using state of the art imaging techniques, astronomers have revealed a vast plume of gas and gigantic bubbles boiling on the surface of star Betelgeuse. The new technique will provide clues to how they shed the mass?

The images show that the whole outer shell of the star is not shedding material evenly in all directions, which may be due to either large scale gas motions caused by heating, or because of the star's rotation. Betelgeuse's atmosphere is bouncing vigorously up and down in bubbles that are as large as the supergiant star itself, and could be responsible for the ejection of the massive plume into space.

Betelgeuse is the nearest star to Earth.

Earth's gravity and solar eclipse

A team of Chinese scientists is planning to conduct a once-in-a-century experiment on July 22, the day of the total solar eclipse, which would test the controversial theory that gravity drops slightly during a total eclipse.

According to a report in New Scientist, geophysicists from the Chinese Academy of Sciences are preparing an unprecedented array of highly sensitive instruments at six sites across the country to take gravity readings during the total eclipse due to pass over southern China on July 22.

The results, which will be analyzed in the coming months, could confirm once and for all that anomalous fluctuations observed during past eclipses are real.

The first sign that gravity fluctuates during an eclipse was in 1954, when French economist and physicist Maurice Allais noticed erratic behaviour in a swinging pendulum when an eclipse passed over Paris.

Pendulums typically swing back and forth as a result of gravity and the rotation of the Earth. At the start of the eclipse, however, the pendulum's swing direction shifted violently, suggesting a sudden change in gravitational pull.

In the run up to July's eclipse, Chinese researchers have prepared eight gravimeters and two pendulums spread across six monitoring sites.

At over five minutes, the event will be the longest total solar eclipse predicted for this century.

Venus nicknamed as Earth's twin

Venus and Earth both share a similar size, gravity and bulk composition and hence, sometimes it is nicknamed as Earth's twin. But with a thick cloak of sulphuric acid clouds and a surface pressure nearly one hundred times that of Earth , makes it less hospitable than Earth. Venus once possessed Earth-like oceans, which evaporated into space to leave a barren landscape.

Venus is a big planet, being heated by radioactive elements in its interior. Some areas in Venus appear to be composed of darker rock , which shows relatively recent volcanic flows.

Both Russia and America sent probes to Venus during the 1970s and 80s – Venera and Pioneer, respectively – that sampled rocks made of basalt. Basalt is formed from cooling lava erupted by volcanoes, and, as is the case on Earth, where magma up-wells along ocean ridges to make new oceanic crust.

The new map of Venus reveals lighter coloured and older rocks with characteristics similar to Earth's granitic continents. Granite is created when basaltic rocks are forced down into the fiery interior of the planet by the process of plate tectonics, which builds and destroys the Earth's crust in an endless cycle. Water combines with the basalt to form granite and the mixture is reborn through volcanic eruptions.

According to the planetary scientists if there is granite in Venus then there must have been ocean in the past.

New images of Saturn by Cassini

The Cassini imaging team have released a set of never-before-seen images and movies of the Saturn system to coincide with the opening of a week-long celebration of the mission at the Royal Observatory, Greenwich.

Cassini has been orbiting Saturn since 1 July 2004 and is now in its Equinox mission phase that will see the giant planet experience equinox this August, the twice-yearly occasion when the Sun passes through the plane containing the planet's rings. For Saturn this occurs once every 15 Earth years.

Cassini finds Titan's clouds hang on to summer

Cloud chasers studying Saturn's moon Titan say its clouds form and move much like those on Earth, but in a much slower, more lingering fashion.

Their forecast for Titan's early autumn -- warm and wetter.

Scientists with NASA's Cassini mission have monitored Titan's atmosphere for three-and-a-half years, between July 2004 and December 2007, and observed more than 200 clouds. They found that the way these clouds are distributed around Titan matches scientists' global circulation models. The only exception is timing -- clouds are still noticeable in the southern hemisphere while fall is approaching.

As summer changes to fall at the equinox in August 2009, Titan's clouds are expected to disappear altogether. But, circulation models of Titan's weather and climate predict that clouds at the southern latitudes don't wait for the equinox and should have already faded out since 2005. However, Cassini was still able to see clouds at these places late in 2007, and some of them are particularly active at mid-latitudes and the equator.

Titan is the only moon in our solar system with a substantial atmosphere, and its climate shares Earth-like characteristics. Titan's dense, nitrogen-methane atmosphere responds much more slowly than Earth's atmosphere, as it receives about 100 times less sunlight because it is 10 times farther from the sun. Seasons on Titan last more than seven Earth years.

Scientists will continue to observe the long-term changes during Cassini's extended mission, which runs until the fall of 2010. Cassini is set to fly by Titan on June 6.

Big planet, small star

One of the smallest stars in the Galaxy has been found to have a planet orbiting it that is six times more massive than Jupiter. This gas giant is as far from its star as Mercury is from our Sun, but because the star is so small, it is like a scaled down version of our own Solar System, with the planet where Jupiter would be. This raises the possibility that there could be even more planets that are rocky like Earth even closer to the star.

The star in question is a red dwarf called VB 10. For a time it was one of the smallest stars known to exist. Red dwarfs are the most common type of star in the Galaxy, and are the coolest.

How to search for alien seas

The search for habitable planets around other stars has taken a step forward by, ironically, looking at our own planet. To test whether we would be able to detect oceans on exoplanets, researchers used the Deep Impact spacecraft to observe Earth, as if we were aliens looking at Earth with the tools we might have in ten years.

The Deep Impact spacecraft hit the headlines in July 2005 when it fired a copper projectile into the comet 9P/Tempel 1, creating a huge outburst on the comet’s icy surface. Since it still has fuel and power, astronomers have since been employing it in other jobs. For instance, at the beginning of this year it began using its cameras to search several stars for the telltale dips in light that indicate transiting planets.

Did life need asteroid bombardment?

A period 3.9 billion years ago when Earth was peppered with impacts by large asteroids may have created an environment in which primitive life could take hold, rather than destroying that life. This is the bold new claim by astrobiologists at the University of Colorado at Boulder, USA.

What we know today as the Late Heavy Bombardment (LHB) hit all the inner planets around 700 million years after the Solar System formed. The Moon and Mercury still bear the scars from this frightful time when fire and rock rained down from the heavens on a regular basis. Nobody is sure what caused the LHB, but the outward migration of the giant planets such as Jupiter and Saturn may have been enough to disturb the orbits of various comets and asteroids, slinging them in our direction.

Exotic dust in comet trail

Comet dust caught in the upper reaches of Earth's atmosphere and scooped up by a NASA aircraft had been found to contain grains of dust dating back to before our Solar System formed. Dust like this is worth its weight in gold for telling us about the original conditions in the solar nebula that formed the planets.

The dust is from comet 26P/Grigg-Skjellerup, which last passed through the inner Solar System in 2002. A year later, Earth itself passed through the trail of the comet, and the NASA aircraft climbed to catch the dust. It was then handed over to a consortium of UK, US and German astronomers who found various chemical treasure troves, including in one dust particle four grains of silicate material that date back to before the formation of the Sun.