The Earth's dust ring

This is a map of the whole sky, showing its brightness at 12 micron wavelength. The image was made with the Cosmic Background Explorer satellite. The detectors could only look between 60 and 120 degrees from the Sun, because of restrictions on how hot the satellite can get, so the middle and edges were not observed. The brightness peaks in directions that are closest to the Sun and that are closes to a horizontal line through the middle of the picture. This line is the plane of the Earth's orbit, called the ecliptic. The brightness is due to interplanetary dust, which is the product of asteroid collisions and dust ejection from comets, and this dust is mostly near the same plane as the orbits of the planets.

This picture is similar to the first one, but a simple model for the interplanetary dust distribution was subtracted first. The simple model has a very smooth and symmetric shape. The leftover emission, shon in this figure, is lumpy and not symmetric. There is a bright spot in the left-center of the picture. This direction is the one looking just behind the Earth in its orbit. There is a similar, but much fainter spot, looking ahead of the Earth in its orbit. These spots are due to a ring of dust that fills the Earth's orbit.