In the early years, the universe is small and extremely hot. All the matter existed as a dense plasma. Plasma (one of four fundamental states after solid, liquid, and gas) absorbed light, making the universe opaque (preventing light from traveling through, therefore not transparent). As the universe expands, so does the matter and energy inside it. What started as light released at that moment has now been stretched into the microwave region. Microwave radiation, WMAP can peer backward in time to when that radiation was emitted.

From 1989 to 1993, COBE tested many theories that predicted by the existence of a Big Bang and collected evidence to develop future questions. The data found agreed with the scientists’ predictions, it left a lot of questions unanswered.

WMAP was launched on June 30, 2001, placed in six-month orbit around the L2 Lagrange (1.5 million km from Earth). WMAP created an extremely precise full-sky map of the cosmic microwave background, improving upon the maps by COBE.

WMAP answered that the Universe started flat and aged 13.8b years ago. It also showed that dark energy is an unknown force that counteracts gravity, pushing galaxies away from each other rather than causing attract one another as we would expect if gravity were the only force at work.

After 9 year of accumulation, it also helped to prove that the Universe’s expansion is accelerating.