By Sheila Vincent, Delaware Nature Society Group Programs Coordinator
One look at our “sister planet” (so called because it is closest to us and almost as large) blazing in the evening sky this month will convince you that she is aptly named. Only the moon outshines her silvery brilliance. Find her above and to the right of Orion, fairly low in the southwest, radiant even through the post-sunset glow.
Catch this lovely sight every clear night that you can. Venus will set a little earlier each evening, and be lost in the glare of the sun by the end of May, returning to morning visibility in late June. This is because Venus is closer to the sun than Earth is – orbiting at “only” 67 million miles away, compared to Earth’s 93 million-mile distance. As we turn toward nighttime, the sun and anything close to it in the sky rotates out of view. We therefore never see Venus (or Mercury) during late hours. It also means that, like the moon, Venus has phases! Binoculars, spotting scope, small telescope, even a good telephoto lens trained on the planet right now will show you a bright, thin crescent:
Venus’ brilliance is not due mainly to its nearness to Earth, but to the fact that it is shrouded in clouds. That highly reflective blanket is both a blessing and a curse; it makes the planet appear intensely bright, but masks, and partly causes, the true nature of the that world’s hellish environment. Venus’ atmosphere is mostly carbon dioxide; we are all too aware of the heat-trapping properties of that particular gas. The clouds further contain solar radiation, causing a runaway greenhouse effect of epic proportions. Venus has an average surface temperature of almost 900 degrees Fahrenheit – hotter even than Mercury’s, and high enough to melt lead. As if that weren’t enough, the atmosphere is so thick that its pressure is equivalent to what you would encounter a mile deep in Earth’s oceans. And then there are the clouds themselves…they are composed mostly of sulfur dioxide, which means that instead of life-giving water, rains on Venus bathe the planet in sulfuric acid!
Cylindrical Projection Full-Surface Map Showing Chaotic Venus Terrain: Mountains (highest is Maxwell Montes at about 20,000 feet), plateaus, lowlands, volcanoes, lava flows, large craters, dominate this world’s geography. There are yet another couple of oddities about our sister world’s unbelievably hostile environment: Unlike the other planets in our solar system (except the special case of Uranus, which is lying on its side), Venus rotates backwards – from east to west instead of west to east!
This bizarre rotation takes about 243 Earth-days, yet Venus takes only 225 Earth-days to complete one orbit around the sun – making its day longer than its year! Take a day off work or school on Venus and return over a year later – no questions asked.
Searing heat, crushing atmospheric pressure, sulfuric acid rain, constant volcanic eruptions…perhaps our sister planet, so beautiful on the outside, is really our evil twin!
Intrigued by what you see in the night sky beyond Venus? Wondering how everything works up there? Join us for for our live Zoom Astronomy series, Thursdays, May 21 and May 28, 6:30 – 8 pm. Learn how to find your way around the stars, constellations, galaxies, and planets that make up our captivating universe.