... Enjoy the wonders of dark skies

A breathtaking Occultation of Venus by the Moon
A routine, but, beautiful celestial event on the 18th of June 2007

For the astronomically minded citizens of Delhi, Nehru Planetarium and Vigyan Prasar, in collaboration with Science Popularisation Association of Communicators and Educators (S.P.A.C.E., an NGO) and the Amateur Astronomers Association of Delhi (AAAD), conducted a public sky-watch at the Jantar Mantar on the evening of the 18th for the Lunar Occultation.

A lot of activities ad well as masonry instrumental and telescopic observations were planned, the highlights of the event being the measurement of the changing angle between Moon and Venus using the Jai Prakas and observations using the 11" computerised GOTO telescope of the Vigyan Prasar.

On the 18th of June 2007, the Crescent Moon and Venus were viewed very close to each other, in the western skies, immediately after sunset. They were a breathtaking pair. As the evening progressed, the Moon was seen to approach Venus and at 9:30 PM (as seen from Delhi) moved in front of Venus. We thought that this view may be a little difficult to catch, from a city like Delhi, as light pollution, dust and haze makes it difficult to view objects close to the horizon and at the time of disappearance, Moon and Venus were just about 10 degrees above the horizon. Amazingly, the western horizon was clear of dust, haze and clouds, and the truly beautiful sight of bright Venus slipping behind the dark portion of the Crescent Moon was granted to all of us at Delhi.

The sky-watch started at 5:00 PM at the Jantar Mantar, with Sun observations using the Ram Yantra. Observations of the Sun through telescopes equipped with filters, was conducted by the Observers from the Vigyan Prasar while the Planetarium staff demonstrated observations of the Sun through projection, using a dobsonian telescope. Some pinhole camera usage for observing shadowy movements of objects, lit by bright sunlight, was also part of the fun activities before the Sun set.

The changing angle between Moon and Venus was measured using the Jai Prakas. Angle measurements were made by the visitors who were given help to make these measurements on their own. Amazingly, the accuracies obtained by absolute newcomers was within a 3rd of a degree with respect to the actual value. Much better accuracies in angle measurements are expected with seasoned observers. See detailed report here.

Visitors were able to appreciate the actual usage and possible accuracies that the giant masonry instruments Ram Yantra and the Jai Prakas of the Jantar Mantar can achieve, as well as appreciate movements of the Moon and Planets in the sky against the relatively unchanging background of stars.

After sunset, in the lawns to the east of the Ram Yantra, several telescopes belonging to the Vigyan Prasar, S.P.A.C.E., AAAD and the Nehru Planetarium were setup for observing the event as well as Jupiter and Saturn. Amazing views of the craters of the Moon and Venus in half phase were seen through projection of the images captured by the Vigyan Prasar 11" telescope. People also had their fill of viewing through the various telescopes set up, the changing views of Moon and Venus as well as the Moons of Jupiter and the rings of Saturn.

The finale was the actual occultation, which was captured by a 130 cm Newtonian Telescope of AAAD Member (Wing Commander Venkateshan, Indian Air Force) with a modified web cam. In the process he was also able to get a video clip of the event.

Some of the images obtained are here.

Lunar Occultation of Venus is a routine, but, a breathtakingly beautiful event. Normally, this would not even require a telescope or any other equipment to view, as Venus is usually bright enough, not to be washed out by the glare of the Moon. Occultation of Venus by the Moon also happens when the Moon is in a crescent phase, thereby reducing the glare of the Moon.

A lunar occultation occurs when a celestial body appears to have moved behind the moon. Such events happen very frequently, but in most cases the star being occulted may be very faint. However, when bright stars or planets such as Venus are occulted by the moon, the event can be seen with the naked eyes.