The Universe Is Thought
To be 13.8 billion years old according to some fairly accurate estimates made by scientists.
According to Space
This number was calculated by looking at the ages of the objects in the universe and how quickly it is expanding.
Stars Are Studied to Help Provide
A starting point for this determination, using justification that the universe's objects cannot be any older than the universe itself.
Only So Much Fuel Is Available
For the gas giants to keep them burning. The first stars in the universe exploded rather quickly (in the cosmic sense)
Filling the Fledgling Universe
With stardust, knowing that the bigger the star, the more fuel it takes to keep it glowing.
Microwave Anisotropy Probe (WMAP) and the European Space Agency's Planck Spacecraft.
Both of Them Studied
Measured, and mapped the cosmic radiation that remains after the Big Bang.
This Made It Possible
To calculate the universe's expansion rate which is believed to be faster than the speed of light.