Missing Venus

When Galileo looked at the heavens through his early telescopes, he saw many cosmic wonders. One of the most astounding was the planet Venus, which went through a cycle of phases just like the Moon’s.

Venus shows phases because its orbit is inside Earth’s orbit around the Sun. Venus is “new” when it crosses between Earth and the Sun, so its nightside faces our way. It’s “full” when it passes behind the Sun, so its dayside faces our way. And in fact, Venus is passing behind the Sun today — a point called superior conjunction.

But although Venus is full, it’s also hidden in the Sun’s intense glare. It won’t return to view for weeks, when it will appear as the “evening star.”

By then, a telescope will show Venus in its gibbous phase — it’ll be daylight across most of the planet’s Earth-facing hemisphere. But Venus will be near its greatest distance from Earth then, so it won’t shine at its brightest.

Instead, the planet is brightest when it’s in its crescent phase. Although most of the hemisphere visible from Earth then is dark, the planet is especially close, so it looks bigger. And at closer range, more of the planet’s reflected sunlight reaches Earth — making the brilliant planet even brighter.

Look for Venus to reappear late next month and climb into better view in the evening sky in May. And if you have a telescope, keep an eye on the planet as it continues its cycle of phases throughout the year.

Script by Damond Benningfield