The red color is caused by the strong signal in the NEOWISE 4.6-micron wavelength detector, owing to a combination of gas and dust in the comet's coma.
But UFOvni2012 disagrees with NASA's explanation.
UFOvni2012 says: NASA tries to pass off this photo as a comet, but when has a comet every looked red?
No comet could emit a red light as it travels though space, however a static field around a spaceship could create such a color.
This is a UFO seen in 5 different positions. I ask you, have you ever seen a comet glowing red?