Then, at the moment of second contact, when brilliant sunlight is completely obscured, a bright red streak might be seen for a few seconds along that section of the Moon’s rim that has just extinguished the Sun. This streak is the chromosphere, which lies above the photosphere and which was first clearly described by George Airy in 1842 during a solar eclipse that he saw from Italy. He was looking at the eclipsed Sun through a telescope and saw what to him looked to be a range of bright red mountains. Today these “mountains” are known as spicules, and in appearance—in photographs much more detailed than Airy could have seen—have been likened to choppy sea waves or to a prairie fire burning through windblown grass. Actually, they consist of millions of gas jets. To put the chromosphere in perspective, the gases of this layer are about 5,000 degrees hotter and a million times less dense than the gases of the photosphere.