BIRTH OF A STAR
1. DESCRIBE THE BIRTH OF A STAR?
Ans: Stars are born when clumps of gas in space are drawn together by their own gravity, and the middle of the clump is squeezed so hard that temperatures reach 10 million C, so a nuclear fusion reaction starts.
2. WHAT IS A STAR?
Ans: Stars are gigantic glowing balls of gas, scattered throughout space. They burn for anything from a few million to tens of billions of years. The nearest star, apart from the Sun, is over 40 trillion km away. They are also distant that we can see stars only as pinpoints of light in the night sky, even through the most powerful telescope. As far as we can see there are no other large objects in the universe.
3. HOW MANY STARS ARE THERE?
Ans: It is hard to know how many stars there are in the universe most are much too far away to see. But astronomers guess there are about 200 billion billion.
4. WHAT IS THE BIGGEST STAR?
Ans: The biggest stars are the super giants. Antares is 700 times as big as he Sun. There may be a star in the Epsilon system in the constellation of Auriga that is ,860 million (3 miles billion km) across 4,000 times as big as the Sun!
5. WHY DO SOME STARS THROB?
Ans: The light from variable stars flares up and down. “Cepheid” are big young stars that pulsate over a few days or a few weeks. “RR Lyrae” variables are old yellow stars that vary over a few hours.
6. WHAT ARE CONSTELLATIONS?
Ans: Constellations are small patterns of stars in the sky, each with its own name. They help astronomers locate things in the night sky.
7. HOW HOT IS A STAR?
Ans: The surface temperature of the coolest stars is below 3,500° C: that of the hottest, brightest stars is over 40,000°C.
8. WHERE ARE STARS BORN ?
Ans: Stretched throughout space are vast clouds of dust and gas called nebulae. These clouds are 99% hydrogen and helium with tiny amounts of other gases and minute quantities of icy, cosmic dust. Stars are born in the biggest of these nebulae, which are called giant molecular clouds. Here temperatures plunge to -263 C, which is just 10° short of absolute zero. These nebulae are thin and cold, but contain all the materials needed to make a star.
9. WHAT MAKES STARS TWINKLE?
Ans: Stars twinkle because the Earth’s atmosphere is never still, and starlight twinkles as the air wavers. Light from the nearby planets is not distorted as much, so they don’t twinkle.
10. WHAT MAKES STARS GLOW?
Ans: Stars glow because the enormous pressure deep inside generates nuclear fusion reactions in which hydrogen atoms are fused together, releasing huge quantities of energy.
11. WHAT COLOR ARE STARS?
Ans: It depends how hot they are. The color of medium sized stars varies along a band on a graph called the main sequence from hot and bright blue-white stars to cool and dim red stars.