Communication S...

The colour of a star is an indication of its

Which of the following is coldest planet?

The sun revolves around the galaxy with a speed of 250 km/sec and and it\'s radius is 3 × 10⁴ light year. The mass of the milky way is

There are certain types of stars called visible stars which undergo periodic change in their light output. If such a star quadruple it\'s light output, how much does it\'s magnitude change?

A particular emission line, detected in the light from a galaxy, has a wavelength λ\' = 1.1 λ, where λ is the proper wavelength of the line. The galaxy distance from us

Assuming that the dimmest visible star to the naked eye has a magnitude of about 6. Brightness of planet Venus (magnitude = –4) w.r.t. this star is

A galaxy is observed to be moving with a velocity of 8600 km/sec^–1. If it is at a distance of 430 million light year from us, Hubble constant and corresponding age of the universe are respectively

Consider a binary star system consisting of two stars of masses M₁ and M₂ separated by a distance of 30 AU with a period of revolution equal to 30 years. If one of the two stars is 5 times farther from the centre of mass than the other. The masses of the two stars in terms of solar masses are

A planet of mass m moves in an ellipse around the sun of mass M_s so that its maximum and minimum distances are r₁ and r₂ respectively. The angular momentum of the planet relative to the centre of the sun is

The Percentage of Sun\'s total energy which reaches the earth\'s surface is