Because of this, we know exactly how massive the sun and all the planets are. Next, astronomers can estimate the mass of the galaxy by adding up all the stars, dust, and gas seen in the galaxy. But I'll outline some possible candidates for dark matter. These would be things like planets and asteroids that may be wandering through the galaxy. Since these objects do not give off their own light, they would be almost invisible.
Neutrinos are particles that are known to exist.
The sun makes zillions of neutrinos every second during nuclear reactions. Neutrinos are very hard to detect - billions pass through eve3ry square inch of your body each second, but in your lifetime, only 1 or 2 will actually collide with an atom in your body. Physics predicts that neutrinos should be massless, but recent experiments have shown that neutrinos most likely have some, albeit a very tiny, mass. If they have mass, they have gravitational pull. Many people are working hard to detect these.