The universe is 10 to 20 billion years old
Not wrong, but our understanding became significantly more precise.
TaughtThe universe is somewhere between 10 and 20 billion years old. Estimates vary widely and astronomers disagree.
Now13.8 billion years, known to better than 1%. WMAP delivered the first precise figure in 2003; Planck refined it in 2013.
What actually happened
This is a refinement, not a correction. Your textbook's range contained the right answer. It was just embarrassingly wide, and it papered over a real crisis: some estimates of the universe's age came out younger than the oldest stars in it, which is impossible.
NASA's Wilkinson Microwave Anisotropy Probe measured the cosmic microwave background with enough precision to pin the age at about 13.7 billion years, and the European Space Agency's Planck mission tightened it to 13.8 billion. The era of cosmology as an order-of-magnitude science ended roughly the year that data landed.
If you graduated before 2003, you were taught a number with a factor-of-two uncertainty. Students today are taught a number with a margin of about 20 million years, which sounds enormous until you notice it is 0.1%.
Newsletter
Get new weekly revisions
Sources
- NASA: WMAP mission resultsmap.gsfc.nasa.gov
- ESA: Planck and the cosmic microwave backgroundesa.int
Who was taught this
Still standard through 2004, so anyone who finished school between 1950 and 2003 learned the earlier version.