Caltech’s fourth annual Media and Science Symposium,...

Caltech’s fourth annual Media and Science Symposium, “The 21st Century: The Multimedia Age,” will feature prominent journalists and scientists in a discussion about the relevance of traditional media in the face of emerging new media. David Gergen, U.S. News editor-at-large and former presidential advisor, will be the keynote speaker. Thursday from 9 a.m. to 2 p.m. in Ramo Auditorium. (818) 395-3227.

ENVIRONMENT

Ventura County will sponsor free Compost Education Day programs May 17, discussing composting basics, resource-efficient yard care and worm composting.

Thousand Oaks: A workshop on composting and beneficial insects will run from 9 to 11 a.m. at Conejo Creek North Park, Willow Bend Picnic Area, 1379 E. Janss Road. Home composting bins will be sold from 9 a.m. to 3 p.m. Information: 449-2472.

Ventura: A compost workshop and barbecue will be held from 10 a.m. to 12:30 p.m. at the Cornucopia Community Garden on Telephone Road between Kimball Road and Johnson Drive. Information: 652-4525. There will be a bin sale from 9 a.m. to 3 p.m. at the Ventura County Government Center, 800 S. Victoria Ave. Information: 648-9226.

Ojai: Compost workshops will be held from 10 to 11:30 a.m. and 1:30 to 3 p.m. at the Ojai Community Demonstration Garden behind Ojai City Hall, 415 S. Ventura St. A bin sale will run from 9 a.m. to 3 p.m. at the Ojai Park & Ride lot on East Ojai Avenue at Fox Street. Information: 640-2555.

Piru: The Community Center will hold the workshop from 10 a.m. to noon at 802 Orchard St. Compost bins will be for sale to Piru residents. Information: 640-2555.

Santa Susana Knolls-Box Canyon: A compost workshop will be held from 9 to 11 a.m. at Santa Susana Park, 6503 Katherine Road. Information: 640-2555.

ASTRONOMY, SPACE SCIENCE

Comet Hale-Bopp is still bright in the northwest sky about an hour after sunset, but will soon be too low to view. Griffith Observatory’s live planetarium show, “Comet Watch,” continues through Sunday. There is also nightly comet viewing, except today, using the observatory’s telescope and those of set up by the Los Angeles Astronomical Society and L.A. Sidewalk Astronomers. Call (213) 664-1191 or Sky Report at (213) 663-8171.

The Santa Monica College astronomy program will focus on prehistoric Earth on Friday, May 9 and 16. On May 30, “Observing Earth From Space” will be the subject. All shows are held in Room 1 of the Science Village at 8 p.m. after the Night Sky Show at 7. (310) 452-9396.

A full-scale mock-up of the U. S. living quarters and laboratory of the International Space Station will visit the Griffith Observatory from 12:30 to 9:30 p.m. Saturday and Sunday. (213) 664-1191.

Author Timothy Ferris will discuss issues of cosmology at a Friends of the Observatory lecture at the Griffith Observatory planetarium at 7 tonight. (818) 846-3686.

SCIENCE FOR FAMILIES

“Cats! Wild to Mild” explores the world of cats at the Natural History Museum of Los Angeles County through Sept. 1. Events include a family day from 1:30 to 3:30 p.m. Saturday. General information: (213) 763-DINO; program information: (213) 763-3534.