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00:02:00
Bob Cannard, a Sonoma Valley farmer explains how compost is generated, both by nature and by human gardeners. Cannard creates a special compost 'tea' to use on his bountiful crops

00:00:38
Mike Wiltberger, magnetospheric physicist at the National Center for Atmospheric Research, narrates this artist’s rendering of a coronal mass ejecting from the sun and then impacting the earth’s magnetic field. Animation produced by the National Aeronautics and Space Administration.

0:40:48
On the occasion of Hubble's 15th birthday we unveil two spectacular mosaic images from the telescope, discuss the amazing accomplishments of Hubble during the past 15 years, and look at some of the images from space.

02:03:07
Celebrate the spring equinox at the Mayan ruins of Chichén Itzá, in the state of Yucatan, Mexico. The alignment of the sun on this day creates the appearance of a shadow, in the form of a serpent, that descends the main staircase of the great pyramid. The Live@Exploratorium crew is there to capture the snake on film and to speak with local archaeologists, archeoastronomers, and solar scientists about this amazing phenomenon.

00:03:07
If you’ve ever gone to hear an orchestra play, you know that the performance begins only after a session of tuning. An oft-repeated story tells of a visiting foreigner attending a concert in Paris. Afterwards, when asked which part of the performance he liked best, he replied, “The beginning, just before the man with the stick came in.” Tuning means adjusting the pitch of an instrument. The pitch of a sound depends on its frequency, the number of vibrations per second that produce the sound. For example, plucking a cello string might cause it to vibrate back and forth 200 times each second. You hear that sound as a low pitch of 200 cycles per second, or 200 hertz. An orchestra tunes itself to a very particular frequency, usually 440 hertz, a note known as A 440. The note is played by the oboist, and the rest of the orchestra tunes their instruments to match it. The oboe leads the tuning because of all the instruments, it is least affected by humidity or other weather conditions.

00:02:29
Music is more than meets the ears directly. Just as no sound exists in a vacuum, every space sculpts the sound within it. Like a site-specific equalizer, reflections, absorption, and resonances combine to give each venue a unique acoustic stamp. A subway tunnel is “live” space, rich with reverberations that trap and reflect sound in a well of hard tile. True to their name, “dead” spaces do nothing: The only sound heard is what travels directly from instrument to ear. An open field is the ultimate dead space. As you follow this wandering riff, listen to the changes wrought by environment. Distance is also a factor here—the sound you hear is recorded from the camera’s vantage. Which spaces sound live? Which sound dead? Do the acoustic changes affect the feeling of the music? Saxophonist Michael Pearce plays with the Highwater Blues Band in the San Francisco Bay Area.

1:00:11
Watch as the best teachers on the planet battle it out for the title of Iron Science Teacher. In this zany competition teachers will have ten minutes to create a science activity. This week's "secret" ingredient - Valentine gifts!

00:02:48
Stepping is rhythmic movement that uses the hands and feet as an instrument. Known best among African American fraternities and sororities, stepping draws on a long African tradition of using the body to make music. Synchronized movement and chants are coordinated by the leader, or step master. Sometimes improvising, always cultivating their own distinctive moves and rhythms, step teams reflect and reaffirm both the unity and the unique style of their group.

00:45:44
NASA's Mars Exploration Rovers, Spirit and Opportunity, have long outlived their life expectancy of three months. Join us as we sum up the rover data and explain how this information changes our view of Mars.

00:46:28
After a week of analyzing the data from the Huygens probe, do scientists think of Titan differently? What were the unexpected findings? Which hypotheses were wrong? Which were correct? Join us as we talk to mission scientists at NASA's Jet Propulsion Laboratory and get the latest on this enigmatic moon.