Peeking at Venus

Venus spends October racing from its point of greatest brilliancy at the start of the month to its dimmest as Venus' dark side faces us at the end of the month. The change is very swift because Venus is closer to us than at any other part of our orbits bringing our relative angular velocity to its maximum. Starting in November Venus will become a morning star, leaving us with only Jupiter and Saturn very late in the evening.

European cultures tended to treat the Sun and the Moon as the basis of time. A year was one cycle of the Sun through the heavens and the month a cycle of the Moon. However this was not the case with New World cultures such as the Maya. For the Mayans, the most significant time periods were based on repetitions of Venus appearing near significant stars. Mayans believed that periods of great change occur at the end of the Venus cycles. This cycles takes more than 400 years to repeat, and coincidentally one was ending just as the Spanish Conquistadors made their first landing. Seeing this as an omen Montazumu was unwilling to oppose these invaders until it was much too late.

The Spanish destroyed huge amounts of Mayan records and culture. Not only did the Spaniards melt down every scrap of gold they could find but they burned Mayan tablets (a form of book or ledger) and Mayan quipu (long cords with knots used to keep numerical information). The Spanish were afraid that these records were the work of the devil. Certainly the Spanish feared any kind of communication which they could not understand. In the process of erasing Mayan literacy, the Spaniards destroyed the greatest astronomical library in the ancient world. Only the burning of the library at Alexandria was as great a lost to history.

Interestingly the Mayan often indicated that Venus was a crescent just as the Moon is a crescent at times. We have been quick to assume that the Mayans may have deduced this from the lunar cycles and they well may have done so. However a more intriguing possibility exists. At their high elevations, Venus can be seen as a tiny disk to people with very sharp vision. Mayans may actually have seen Venus as a crescent centuries before Galileo turned his telescopes skyward.

This brings the interesting question: can we actually see the crescent of Venus without using telescopic aid? The answer is a resounding - well maybe. Venus is certainly large enough to be seen. While tiny, it is a disk, not a point of light. The real problem with Venus is that it is dazzlingly bright, causing the air around it to be illuminated to the point that the whole image is slightly blurry. The trick to seeing Venus as a crescent is to cut out all the excess glare, leaving only Venus itself. This isn't as hard as it might seem. Take a piece of stiff opaque material. (Metal foil over a coat hanger wire frame will do just fine.) Make a neat pin point hole as circular as you can make it. Sight Venus through the pin hole and move the pin hole in and out until Venus appears clearest. With luck, you may just glimpse one of the rarest things a human eye can see - the shape of another planet without optical aid.

Kids actually may have a better chance seeing the crescent than adults. Their younger eyes are less cloudy, they have more supple corneas and they are more receptive to light. Oldsters such as myself try to make up the difference with viewing experience kids usually beat us with their fresh young eyes.

So if you see someone down on the seawall at Watch Hill or the Pavilion at Misquamicut squinting through some aluminum foil stretched across a wire frame, its probably just me. Don't be surprised if it is daytime. I often spend time tracking down Venus as much as an hour before sunset.

Fairly reliable reports of seeing Jupiter's moons without telescopic aid exist. Just as with Venus the problem is that Jupiter is too bright. Jupiter's moons are fifth magnitude, faint but brighter than the seventh star in the Plieades which is routinely reported as visible. However if Jupiter is hidden momentarily, and the moons are not hidden they become visible. Utility pole wires make good tools to hide Jupiter. They are thin enough not to hide too much.

I have to be honest. I've never seen Venus as a crescent or Jupiter's moons without a telescope. I would be very pleased to learn if you have success with either.

Leslie Coleman
Leslie Coleman
Entry Date:
Oct 1, 2002
Published Under:
Leslie Coleman's Columns
Subscribe to Leslie Coleman's Columns RSS Feed