Want to watch a once-in-a-lifetime astronomical delight this week? Buy your solar glasses soon.
In Los Angeles, the city-run Griffith Observatory is one of the few known places that is selling equipment for people to view the Transit of Venus directly. Solar glasses are on sale at the Griffith Observatory gift shop for $2.99 -- but the gift shop is only open until 9 p.m. Sunday, and the observatory will be closed Monday. The next chance to buy the glasses at the Observatory will be Tuesday after 12 p.m., just three hours before Venus travels across the Sun.
The Transit of Venus is a rare astronomical event, where Venus will cross in front of the sun from the Earth's perspective, producing a small, visible dot that will glide from left to right across the top of the solar disk. The next time people anywhere on Earth will be able to see such an event will be in 105 years.
The event will begin shortly after 3 p.m. Pacific Daylight Time, but the sun in California will set before Venus completes its journey across the sun.
You can also try to find so-called No. 14 welder's glasses that might be on sale at welder's shops or at home improvement stores. You can also catch a NASA broadcast of the transit, or head to the Observatory on Tuesday afternoon to watch it through a telescope with a special solar filter.
You could try using a pair of binoculars, preferably with a magnification power above 7, to project the sun's light onto the sidewalk or a piece of paper. If you're able to find an image of the sun, look for a tiny dot showing the image of Venus.
But pinhole projectors used during the eclipse probably won't work this time, experts say, because they don't have enough resolution to show the planet's shadow.
According to an online video from Slooh Space Camera, astronomers used the Transit of Venus to calculate the size of the solar system.
Knowing it was so rare, countries sent out ships around the world "to time, to the second, how long it took the disk of Venus to move from one edge of the sun to the other," the video said. It was from this data that scientists were able to calculate the distance of the Earth to the sun, according to the video.
Those with the best seats for Venus' transit will be in eastern Australia, New Zealand and eastern Asia, weather permitting. For those west of the International Date Line, the eclipse occurs on Wednesday.