The Wilkinson Microwave Anisotropy Probe (WMAP) has been recording data for 5 years on heat in the form of microwaves created by the Big Bang. What it's found, to an amazing degree of precision, is that the Universe is 13.73 billion years, plus or minus 120 million years. Not 6000 as some Creationists claim based on exactly no data.
Kelvin. That tiny difference shown by the colors above is only 0.0002 degrees Celsius.
WMAP was also able to determine the kinds of energy and matter that make up the Universe that 72.1% dark energy, 23.3% dark matter, and 4.62% regular stuff.
Everything you see around you, all the massive stars, are the galaxies are less than 5% of what is. And every atom in your body was created in a star.