William Herschel often gets the credit, but his sister Caroline was also a pioneer astronomer. For more watch NOVA's Hunting the Edge of Space airing April 6 and 13 on PBS. www.pbs.org/nova/telescope

"Hunting the Edge of Space" produced for NOVA by Brook Lapping Productions and TPT National Productions, in association with Green Umbrella Films, LLC

NOVA is produced by WGBH in Boston. Funding for NOVA is provided by ExxonMobil, David H. Koch, the Howard Hughes Medical Institute, the Corporation for Public Broadcasting, and public television viewers.