Mauna Kea is Hawaiian for "white mountain". The volcano is over 14,000 feet in elevation and occasionally gets snowfall. You can drive up to the visitor center at 9,000 feet and have great views across the saddle of Mauna Loa and of the night sky as you peer through telescopes.
Stargazing programs are from 6:00 pm to 10:00 pm every night. Visitors are not allowed to the summit after dark. Mauna Kea is about an hour to 1 1/2 hours drive from Hilo. Be careful of sharp turns on the Saddle Road and remember to bring warm clothes.