Mayilsamy Annadurai is ISRO’s programme director for the remote sensing satellite RISAT 1. He was also the project director of the Chandraayan-1 mission and is in charge of the Chandrayaan-2 mission. Before he took over the Chandraayan mission he was in charge of India’s National Communication satellite (INSAT) missions. He has a Ph.D from Anna University of [...]
Astrophotography
May 3, 2012 By Leave a Comment
Although by early 1850s photographs (daguerreotype) of the Sun, Moon, and a few bright stars were obtained, real astrophotography started with the availability of the so-called ‘portrait objectives’- special lenses that were developed primarily for portrait photography. The distinctive feature of these lenses was their medium focal length and large aperture, with the ratio between [...]
Collodion Plates
May 3, 2012 By Leave a Comment
Although daguerreotypes produced very clear images, they required lengthy exposures and it was a ‘once-only’ process; copies of the image could not be made. It was also expensive. British sculptor Frederick Scott Archer’s development of the ‘wet collodion’ process-forerunner of modern photographic film- changed the face of photography; it enabled the making of finely detailed [...]
The Daguerreotype
May 3, 2012 By
By the end of the 18th century it was known that many silver compounds were blackened by sunlight, and that the black colour was due to the formation of minute particles of silver, which could be used to record ‘images’ in black and white. But initial attempts were not encouraging, as it was not possible [...]
Messages in Starlight
May 3, 2012 By Leave a Comment
The astronomical discoveries till the middle of the 19th century were not much different from the trend in the previous two centuries. The positions of the stars and planets were recorded with precision using simple visual sighting through telescopes. If the objects were larger, such as star clusters and nebulae, they were described in notes, [...]
Kepler Mission – The Search for Earth-like alien planets
May 3, 2012 By Leave a Comment
A unique mission was launched by NASA in March 2009 when a spacecraft especially designed to search for Earth-like planets was launched on a 3.3- year mission. Kepler Mission The Kepler mission is designed to search for planets orbiting around other stars by looking for the tell-tale dropping in brightness of a star caused by [...]
Hubble Telescope – A telescope in Orbit
April 19, 2012 By Leave a Comment
A new chapter in optical telescopy was opened in April 1990 with the deployment of the Hubble Space Telescope into an orbit 613 kilometres above Earth. It became the first major orbiting observatory, carrying a 240-cm primary mirror with several instrument packages and cameras able to record various parts of the electromagnetic spectrum. The telescope [...]
Adaptive Optics and Atmospheric Turbulence
April 19, 2012 By Leave a Comment
Even as telescope designs improved and larger and larger telescopes were built, observation from ground was beset with a serious problem- that of atmospheric turbulence. When light from a star or another astronomical object enters the Earth’s atmosphere, atmospheric turbulence (caused by different temperature layers and different wind speeds interacting) can distort and move the [...]
The Biggest Next Generation Telescopes
April 19, 2012 By Leave a Comment
Very Large Telescope is not the ultimate in optical telescopes. Three large optical telescopes now at the advanced-planning stage will dwarf even the VLT when completed in 2018. The Thirty-Metre Telescope (TMT), to be located on an isolated mountain peak rising 4,475 metres in the Atacama region of north-eastern Chile, is named after its 30-metre diameter [...]
Very Large Telescopes
March 23, 2012 By 1 Comment
In recent years, a new generation of multi-mirror telescopes has been coming up around the world, thanks to new techniques of computer-aided telescope guidance and electronic image processing. The largest of these is the Very Large Telescope of the European Southern Observatory (ESO) at Paranal in northern Chile. Very Large Telescopes It is today the [...]
