Lowell scientists and collaborators studied the 1997 apparition of Comet Hale-Bopp with a number of instruments around the United States.

Periodic comet 103P/Hartley 2 was discovered by Malcolm Hartley in 1986, with the 2010 apparition being its most favorable since its discovery.

This long-period comet passed within 9.3 million miles of Earth on March 25, 1996, making it one of the closest cometary apparitions in two centuries.

Comet Linear (1999 S4) is a long-period comet discovered on September 27, 1999 by the Lincoln Near-Earth Asteroid Research (LINEAR) program.

Comet Tempel-1 is a periodic comet discovered by German astronomer Wilhelm Tempel in 1867.