A partial lunar eclipse will be visible tonight for those living in the Eastern Hemisphere. At 20:09 UTC, the fullest coverage of the moon by Earth's shadow will occur lasting for only 27 minutes. Only two other lunar eclipses this century will have a shorter duration.
Unlike viewing a solar eclipse, lunar eclipses may be viewed by staring directly at them. They also won't require any additional equipment, such as telescopes or binoculars. Areas that have clear skies will be able to see it the same way they'd typically view the moon.
Most of Europe will have good conditions at the time of the eclipse tonight, where it will be visible at 9:09 p.m. WEST in Lisbon, Portugal, to 12:09 a.m. MSK Friday in Moscow, Russia. Cloud coverage on the Mediterranean Coast will give poor viewing conditions to the area. Cloudy conditions will also limit visibility to the southern portions of the British Isles, parts of Scandinavia, and the northern coasts of the Baltic and North seas.
The eclipse will be over Australia from 4:09 a.m. WST Friday, April 26, in Perth to 6:09 a.m. EST in Sydney. Most of the country will have clear or partially clear skies to allow for viewing. Tasmania and most of Western Australia will have increased cloud coverage that will significantly hinder visibility.
Lunar eclipses occur about two to four times a year. Some these are penumbral eclipses, which are so subtle that they hardly look like anything to the average observer.
Shadows have three parts, the umbra, penumbra and antumbra, which are used to describe the relation of the shadow to the degree of light casting it. The umbra is where the shadow is deepest, as the light source is fully blocked by the object casting the shadow. The penumbra and antumbra occur on the edges of the umbra where some of the light source lessens the shadow. The light cast on the moon during a penumbra eclipse obscures the view of the shadow cast, making the eclipse hard to notice.
There will only be two more lunar eclipses in 2013, both of them penumbral. The next easily visible eclipse will be April 15, 2014, seen as either a total or partial eclipse from Australia and eastern Asia across the Pacific to North and South America.
For areas outside of the eclipse's range or with poor viewing conditions, SPACE.com will be holding a live webcast to show it.