She became a professor of astronomy at Vassar when it was founded in 1865, and was the director of the college observatory. A comet is a small celestial body made up of ices, rock, dust, and gases that revolves around the Sun. The head of a comet is composed of 2 parts, the nucleus and the coma . When solar radiation strikes the nucleus, some of the ice is converted to gas, and this gas forms a cloud that surrounds the nucleus. The cloud of gas is the coma.
Comets also grow tails.
This trail of gas and dust forms the comet's tail. A comet's tail always points away from the Sun, regardless of whether the comet is moving toward the Sun or away from it. Often 2 tails form. The charged gas glows with a blue color. The other is called the dust tail and is made of dust that glows white because it reflects sunlight.