• Light Year:
The distance traveled by light at speed of 186,000 miles per seconds in one year is known as a light year. One light year is approximately 9461,000 million kms or 5875000 miles. Light year is also used to measure the distance between the galaxies.


• Astronomical Unit:
The distance between the Sun and the Earth is called as Astronomical Unit. This unit is also used in the measurement of distances between the heavenly bodies within the solar system. The earth is one A.U away from the Sun and the Pluto is 39 A.U away from the Earth.


• Super Nova:
A Super Nova is an exploding star. At the end of its phase as a Red Giant, a heavy star explodes as a Supernova shining briefly as brightly as a thousand million stars. Recent Supernova was observed on the night of Feb 23, 1987. This occurred in Large Magellanic Cloud.


• A New Star Nova /Temporary Star:
A new star nova or temporary star is the name applied to a star which experiences, a sudden and usually considerable increase in brightness after which its light diminishes rapidly and then more slowly. The majority of novae before they outburst, were faint stars, generally showing small fluctuations in brightness.


• Constellations:
Constellations are groups of stars in the sky, which look rather like familiar objects, such as tools, animals and people. Constellations were discovered thousands of years ago. Greek astronomers divided the stars into 18 constellations, many of which they linked to characters from their mythologies. Grouping of the stars into constellations makes them easier to study. Today, there are about 88 constellations. They are named after objects like a Swan (cygnus), an archer (Sagittarius), a net (reticulum) etc.