NASA astronomers measure universe's expansion

NASA astronomers were able to make the most precise measurement yet of the Hubble constant, or the rate at which our universe is stretching apart.

The Hubble constant is named after astronomer Edwin P. Hubble who astonished the world in the 1920s by confirming our universe has been expanding since it exploded 13.7 billion years ago. Astronomers used the Spitzer space telescope to measure the constant.

The newly refined value for the Hubble constant is 74.32.1 km per second per megaparsec. A megaparsec is roughly 3 million light years, Xinhua reported Wednesday.

In the late 1990s, astronomers discovered the expansion is accelerating, or speeding up over time. Determining the expansion rate is critical for understanding the age and size of the universe.

Unlike NASA's Hubble space telescope, which views the cosmos in visible light, Spitzer took advantage of long-wavelength infrared light to make its new measurement.