There’s an area in the night sky called the “Lockman Hole.” It’s found in the constellation of Ursa Major (The Big Bear; the Big Dipper forms the lower body and tail of the larger constellation.) This “hole” appears almost empty to the naked eye and small telescopes. Regions like this one are almost completely devoid of objects in our Milky Way galaxy. With little local clutter in the way the Lockman ideal for studying galaxies in the distant universe.
Here’s what this empty part of the sky looked like when it was surveyed in infrared light by the Herschel Space Observatory. All of the little dots in this picture are distant galaxies. Their collective light is known as the cosmic infrared background. By studying this pattern, astronomers were able to measure various effects of dark matter.
Image credit: ESA