Celestial beauty: Take a peek at Venus at her peak

After the Moon, Venus is the brightest thing in the night sky. Nothing else even comes close. No wonder civilizations through the ages worshiped it. The ancient Egyptians and Mayas were not alone in observing Venus intensely. And yet, these days, most people seem unaware that the most brilliant object in the sky is our sister planet: the nearest celestial body after the Moon.

But Venus is not always there. Sometimes it’s behind the Sun. Sometimes it’s away from the Sun, but very low in our sky, hidden in twilight behind hills and trees. Then, for months at a time, it’s only visible in the pre-dawn east: a gift for early risers and insomniacs.

When it does appear in the evening sky, an apparition that lasts nine months, its visibility depends on the slant of its orbit with the horizon. Think of a dinner plate with a cherry in the middle. If you view the plate from edgewise, and think of the cherry as the Sun and the rim being the orbit of Venus, you can picture the way Venus swings away from the Sun from our perspective. It ventures as far as 46 degrees.

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But some years, that 46-degree spread is virtually horizontal, so that at sunset Venus’ separation from the solar glare is not upward but merely leftward, which keeps it low above the horizon and makes it set almost immediately. However, if it reaches its greatest elongation in late winter or early spring, the plane of its orbit angles almost straight up from the sunset point. That’s what’s happening right now.

This Monday night, the 26th, Venus reaches its greatest separation from the Sun while standing almost straight above where the Sun set. These are rare perfect conditions. It makes Venus appear as high up as is ever possible. In fact, last week, a physician commented to his wife that the superbright star could not be Venus because it was too high! It is 44 degrees high at sunset.

There’s more: Venus is also nearly at its most brilliant. It will easily cast shadows when viewed away from all artificial lights against a white surface. You can watch it any evening. It’s highest up between 8 and 9 p.m. And the planet Jupiter still dangles just beneath it. As a bonus, look east – opposite in the sky where Venus and Jupiter hover – to the only bright-orange star. That’s Mars, which this month is at its own brightest-of-2012 milestone.

For all that, we are about to get an extra treat. This Sunday night, March 25th, the crescent Moon will hover right next to Jupiter, with Venus above them. On Monday night the Moon will float very close to Venus itself. It will be nothing short of spectacular.

We must savor it. A month from now, Venus will be slightly brighter but noticeably lower. During May it plunges lower and lower each evening. On June 5, it passes in front of the Sun. And then its wonderful evening-sky apparition is over.

Next year, Venus will be low and awful. However, since Venus orbits the Sun 13 times in the same interval that Earth makes eight circuits, this exact current apparition will repeat eight years from now, in 2020. Interestingly, the Moon experiences an even number of lunations in that same cycle too, so that these gorgeous conjunctions with the crescent Moon will repeat that year as well.

But why start planning ahead? Right now we have Venus in our grasp. It’s the most spectacular presentation of the evening star that we can ever see.

 

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