Catch comet McNaught this month A comet is an icy body, orbiting in the solar system, which partially vaporises when it nears the Sun, developing a diffuse envelope of dust and gas and, normally, one or more tails. Ground-based observations of the behaviour of many comets, together with results from the investigation in 1986 of Halley’s comet from space probes, support the view first proposed by F Whipple in about 1949 that the nuclei of comets are essentially “dirty snowballs” a few kilometers across.
The first parabolic orbit was calculated by B G Marsden on September 10, 2009. He took 35 positions from the period spanning 2009 July 20 to September 10 and determined the perihelion date as July 2, 2010 (closest point to the sun. The perihelion distance was given as 0.40 AU, indicating the comet could become a fairly bright object. The comet McNaught had passed perihelion one month after the discovery, but was discovered about a day before its closest passage by Earth at 0.567 astronomical units (One astronomical unit = 14, 96, 00,000 kilometers). The widespread observations began near the end of August 2007. The comet’s altitude has stayed fairly low up to early October 2007, which was making it a difficult object for most people. It is true that some observers have reported the comet visible to the naked eye, but the conditions must be exceptional for this to happen.
Comet McNaught can be seen with the help of small binoculars or with the naked eye in the morning sky. This comet is 0.40 AU from Earth.
The comet is visible from all parts of India. The various astronomical devices used to witness this particular comet are Celstron Nexstar11 telescope, Meade F3.3 focal reducer, and Stellacam II video camera. On June 25, the comet will be visible at a magnitude of 2.5. This comet is expected to be a bright one as June progresses. The only problem is that as it brightens it will also be sinking deeper into twilight. The comet will be at its brightest magnitude of about 2 between June 30 and July 2, but it will also be too close to the sun, to actually get a good glimpse.
Mohan Krishna S A
Bubbles bursting in the air
The most mysterious moment in a bubble’s life is when it pops and instantly loses its glorious form. Now researchers have used a high-speed camera to shed new light on what exactly happens when a hemispheric bubble, the kind that might sit on a soapy glass, bursts. A bubble may form a plethora of smaller bubbles when it pops, depending on its viscosity, or how thick and glutinous it is, says a study published in Nature. The viscosity of the bubble is correlated to the daughter bubble effect, said James C Bird, a post-doctoral fellow at MIT and lead author of the study.
Sindya N Bhanoo
New York Times News Service