A、Because the American Astronomical Society offered wrong data. B、Because they included the wrong star systems in their observat

What is the color of the universe? Two American astronomers reported their study of all the light in the universe. They said that the universe would appear to the human eye to be a light greenish color.
Karl Glazebrook and Ivan Baldry of Johns Hopkins University in Baltimore, Maryland, reported their recent finding. They presented research at a meeting of the American Astronomical Society. Their study attempted to show what people might see if they could observe the universe from far away.
The scientists gave a number value to the colors of the different star systems. Then they added the numbers together and found the average measurement. The scientists used this arrange to identify the color of the universe. They said it was a very pretty light green color. They called it "cosmic spectrum green." Many newspapers and television stations reported their finding. Other scientists and color engineers attempted to reproduce the result.
Mark Fairchild of the Rochester Institute of Technology in New York was the first person to identify a mistake. He discovered a mistake in the computer software program used by the Johns Hopkins scientists. When the mistake was corrected, the results changed. The new color of the universe is much less colorful. It is very close to white.
The scientists have apologized for the mistake. They are now working with the Rochester Institute of Technology to produce more images of the color of the universe.
What did the two astronomers from Johns Hopkins University report?

Why did the Johns Hopkins astronomers make a mistake?