‘Super moon,’ eclipse, Venus transit are sky highlights

Posted: May 03, 2012

Don’t look to the heavens for signs of apocalyptic prophecies coming true.

But over the next month, the skies will offer several interesting sights, including a solar eclipse and a rare view of Venus crossing the sun.

Only one sight, though, will be easy to view here. ( Weather-permitting, of course.)

That’s Saturday night’s so-called “super moon,” which will rise shortly before 8 p.m. While it’s near the horizon will be the ideal time for viewing, says Franklin Institute astronomer Derrick Pitts. Rising moons seem extra big because of an optical illusion, but because the moon also will be at its closest point to Earth, its lit disc will be the biggest and brightest this year.

Some might be inspired to try to get a “moon tan” or imagine a reason for weird weekend behavior, but for a true effect, look to tides, Pitts said. Full moons produce strong tides, both high and low, because the gravity of the sun and the moon tug from opposite sides of the Earth.

“With this ‘close’ close approach, the moon will exert 42 times more force on tides than it would at the next apogee two weeks later,” Pitts said. But don’t expect disaster, such as “earthquakes, tidal waves, crime sprees, heart attacks, or volcanic eruptions.”

A super moon happens every year, and “and it seems the Earth has managed to survive each time,” Pitts said.

On May 21, a solar eclipse will be visible in the United States, but it won’t be total anywhere on Earth, or visible on the East Coast.

By that date, the moon will be too far away to block the entire sun, so a ring of sunlight will still show, creating what’s known as an annular eclipse.

Millions on the West Coast, however, will be within a drive of the path for optimum viewing, from the California-Oregon border past Albuquerque, N.M., into western Texas. The eclipse actually begins on May 20, with the path for prime viewing passing over Eastern China and Japan, then curving past Alaska’s Aleutians Islands as it crosses the Pacific Ocean.

Be warned, of course: Looking directly at the sun, even briefly with sunglasses, can cause serious vision damage, so viewers need to use special filters, set up some kind of projection system to avoid direct viewing, or watch a streaming broadcast on a TV, computer or smart-phone. (Here’s a helpful guide to products and other options that also covers the next phenomenon.)

On June 6, Venus will make a rare journey across the front of the sun that lasts for about 6 hours and 40 minutes.

Only seven times has this transit happened since the invention of the telescope, according to NASA: 1631, 1639, 1761, 1769, 1874, 1882 and 2004.

One safe means of viewing is to get a look through a telescope at the Franklin Institute.

“We’ll position scopes to see between buildings to the west for the two-plus hours we get to see the event,” Pitts said.

Note, as the guide linked above points out, crude devices, like pinhole projectors, or unmagnified ones, like special eclipse-viewing “solar shades,” won’t give a sharp enough image to see Venus clearly.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.

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