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Asked by Gibbo345 to Colin, John, Kevin, Shikha, Triona on 10 Nov 2014.
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Kevin Motherway answered on 10 Nov 2014:
Generally the number is guessed at about 100 – 400 Billion stars per Galaxy. A hell of a lot basically. On a really dark night ALL the stars you can see with the naked eye are from a tiny tiny part of the Milky Way Galaxy. You can see the “Milky Way” glow but can’ t make out individual stars with the naked eye. And there’s maybe 100 Billion Galaxies out there.
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Shikha Sharma answered on 11 Nov 2014:
Hi Gibbo345,
I would say around 1 trillion stars. But it’s just a number which we have roughly calculated. The astronomers can’t directly match the number of stars in a galaxy. They use either a method and measure the total light from a galaxy in watts, then divide by the average wattage of a single star; or can count up the total number of stars in a very small region of a galaxy to get the number of stars per cubic light year, then multiply by the total volume of the galaxy or just ‘weigh’ a galaxy by calculating its total mass, then divide this number by the average mass of a single star. But all of these methods have their problems.
I read in a report that “The best estimates suggest that there are at least 70 thousand million million million (70 sextillion or 7 × 1022) stars in the Universe. The Universe probably contains more than 100 thousand million (100 billion or 1011) galaxies.”
Isn’t that awesome?
Comments
Kevin commented on :
Woooah. Two scientist with different answers what’s going on!!! The most important phrase in science is “I don’t know”, its all about getting to an reasonable answer using the scientific method. I think a number of about 400,000,000 is reasonable and Shikha thinks about 1,000,000,000,000, but that’s really only over x2.5 times my answer (not x10 times my answer or what we call an order of magnitude) . When you’r talking about such huuuuuge numbers with loads of zeros such a difference is not all that big. I’ve heard Brian Cox usually says about 100 – 400 Billion depending on what day of the week it is and what conditioner he is using in his hair that week That’s a difference of x4 times so Shihka’s guess and mine are actually closer together (x 2.5) than how much Brian Cox varies his own guesses.