Friday, August 20, 2010

Earth and Moon view from MESSENGER


From the Earth, we can see seven planets Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune. They look fabulous when observed through telescopes like phases of Mercury and Venus, ice capped Mars, mighty Jupiter with its four satellites, beautiful Saturn with its magnificent rings, blue worlds of Uranus and Neptune. Now you may ask the question how our Earth looks from the distance space? Is anybody has seen the Earth from the remote space? Yes, there is one, who looked at the Earth from the remote space. It is MESSENGER a satellite on mission to study the Mercury. Above image taken by the satellite on 6 May 2010. In the lower left portion of this image the Earth can be seen, as well as the much smaller Moon to Earth's right. MESSENGER took this image from 183 million kilometers. To provide context for this distance, the average separation between Earth and the Sun is about 150 million kilometers.

This image was acquired as part of MESSENGER's campaign to search for Vulcanoids, small rocky objects that have been hypothesized to exist in orbits between Sun and Mercury. The MESSENGER spacecraft is in unique position to look for smaller and fainter Vulcanoids than has ever before been possible. Vulcunoids are named after the hypothetical planet Vulcan which was proposed to exists between Mercury and Sun by the 19th century astronomers to attempt explanation in peculiarities of Mercury's orbit. No such planet was ever found.

MESSENGER is a unique mission of NASA to study the Mercury planet after Marinar-10. It was launched on 3 August 2004 from Cape Canaveral, Florida. The name comes from 'MErcury Surface, Space Environment, GEochemistry and Ranging' highlighting the project broad range of scientific goals and it is perfect to study Roman mythological messenger of the gods.
AMOL KATE
:image credits to NASA/John Hopkins Applied Physics Laboratory/Carnegie Institute of Washington

Saturday, August 7, 2010

Solar Tsunami


Last year solar astronomers observed quietest Sun in almost a century. In 2008, there were no sunspots observed on 266 of the year's 366 days (73%). To find a year with more blank suns, you have to go all the way back to 1913, which had 311 spotless days, some observers suggested that the solar cycle had hit bottom in 2008. Sunspot counts for 2009 were almost same as previous year 260 spotless days (71%). Many astronomers said that our sun is now passing through the deepest solar minimum. But, a few days ago suddenly the Sun emitted a massive belch in to space, astronomers christen it Solar Tsunami.
On August 1st at 8:55 Universal Time, orbiting satellites witnessed a sizable flare erupting from the large sunspot region designated 1092. The strength of this outburst was pegged at C3, modest as flare go, but it still triggered an impressive coronal mass ejection, or CME, that shot out from the solar disk at more than 1000 km per second. The CME hit Earth's magnetic field on August 3rd at 1740 Universal Time. The impact sparked a G-2 class geomagnetic storm that lasted nearly 12 hours--time enough for auroras to spread all the way from Europe to North America.

CMEs are the result of strong solar activity or solar storms. It is a large cloud of charged particles that are ejected from the Sun over the course of several hours and carry up to ten billion tons of plasma. They expand away from the Sun at speed as high as a thousand kilometres in second. A CME can make the 150 million kilometres journey to Earth in just two to four days. This CME will have noticeable consequences beyond producing an aurora. Stronger solar storms could cause adverse impacts to space based satellites, space station and technological infrastructure on Earth.

The Sun goes through a regular activity cycle about 11 years long. The last solar maximum occurred in 2001 and its recent extreme solar minimum was particularly weak and long lasting. Experts don't expect solar activity to peak until mid-2013, but these kinds of eruptions are one of the first sign that after oversleeping for more than a year, our star is finally stirring from hibernation and heading toward anther solar maximum expected in the 2013 time frame.

AMOL KATE