Sky Almanac

Throughout May, the gorgeous and stunning planet named after the Goddess of Beauty, Venus, dominated the evening skies. In mid-month it plummeted toward the western horizon. On June 1 it will be barely visible. Then on June 5 it will be moving across the disk of the sun, as a small dark dot, a very rare solar event, known as a transit. The last transit of Venus as seen from Earth occurred in 2004 and the next will be in 2117. Venus is in Taurus at the time of the transit. Mars is in Leo and Saturn is in Virgo, lying just above Spica.

June 1: Some 30 minutes after sunset, Venus will be only 2 degrees above the western horizon.

June 3: Full moon

June 5: Transit of Venus—be very careful! If you have eclipse watching glasses you might be able to see it touching the upper edge of the sun about 3:10. Between then and sunset it will move across the sun to the west, appearing as a large sunspot. But don’t look without eye protection. Hopefully you can find someone with a telescope and very safe filter to watch. Take no chances.

June 10: Third Quarter Moon

June 18: New Moon

June 26: First Quarter Moon

Annular eclipse

I hope many of you watched the eclipse on May 20. I watched it in Pueblo Bonito in Chaco Canyon, which was a pretty exotic experience, surrounded by the walls of the great house and memories of its residents who had abandoned the place by 1150. We were surrounded by many living beings, wearing eclipse watching glasses, which made for great people watching. Near us under the ground of the ancient plaza, were the roots of an ancient pine tree, which may have been understood by the residents as the cosmic axis. The moon reached the center of the sun around 7:30pm amidst whoops of delight. The temperature fell by 10 degrees and the atmosphere took on a strange white glow, a sunset while the sun is still high in the sky. Ravens which had been circling overhead vanished. If you crossed your fingers, you could see multiple images of the sun projected on the ground.

Near the visitors’ center in the canyon there is a rock we call Piedra del Sol. On its northeast side it contains a large spiral petroglyph, which marks June solstice sunrise. On its south side it contains a very odd petroglyph, which may be a depiction of a total solar eclipse that passed through the canyon in July 1097.

Transit of Venus

A transit of Venus occurs when the planet passes directly between the Sun and Earth, as it moves from an evening “star” east of the sun, to a morning “star” west of the sun. A few days after the transit, it will be appearing in our morning skies, behind the Sangre de Cristos. Since the orbital plane of Venus is tilted with respect to the earth and sun, transits occur very rarely, in pairs of eight years and separated by 105 or 122 years. Venus transits are of great historical significance because in the 1700s astronomers traveled vast distances—such as from England to Tahiti—to measure the size of the solar system. By timing how long it took for Venus to cross the sun as viewed from different places on earth, the distance to Venus could be determined. Then comparing the periods of Earth and Venus, the distance to the sun could be established. During the transit of 1761 astronomers noticed a halo of light around the planet’s dark edge, revealing for the first time that Venus has an extensive atmosphere. Now we know that Venus has been a victim of its own case of global warming and is surrounded by a deadly mix of mix of carbon dioxide, nitrogen, and hot sulphuric acid: not the goddess of beauty once thought.

Today transits of planets surrounding other stars have become extraordinarily valuable tools for detecting exo-planets. As a planet passes in front of a star, it temporarily blocks out a tiny portion of the starlight, revealing its presence and providing information about the planet’s size and in some cases its temperature. Using the Kepler space craft, these transits have been found on more than 1000 other stars. For the first time ever, the Hubble Space Telescope will be used to simulate the Venus transit as it would look if viewed by astronomers living on a distant solar system looking at us. The optics of the Hubble Telescope are too sensitive to look at the sun directly—they would be fried. Instead, it will observe the Venus transit by measuring the intensity of sunlight reflected off the moon, which is a million times fainter than direct sunlight. All is not lost if you miss the transit this month. It will be visible from Jupiter on 20 September, and there are plans to measure the intensity of sunlight off that giant planet using the Hubble telescope.

The transit will be visible in its entirety only from the western Pacific, eastern Asia, eastern Australia and high northern latitudes, where it will last 6.5 hours. Astronomers from the Observatory of Paris in Meudon are stationing nine portable telescopes in Japan, China, Australia, and Hawaii to measure the transit with different color filters, to assist in interpretation of transits around other planets. Pluto, you are indeed in good company.