A partial lunar eclipse will be visible over much of the Eastern Hemisphere on August 7, in an advance preview of a total solar eclipse coming two weeks later over the United States.
The partial lunar eclipse will be visible from parts of Europe, Africa, Asia, and Australia, with the peak coming at 6:20 p.m. GMT.
A partial lunar eclipse occurs when the Earth moves between the Sun and the moon.
Experts say viewers will see an initial partial reddening of the moon when the lunar eclipse begins.
Maria Borukha, a lecturer at the St. Petersburg Planetarium, said the partial eclipse should be observable over much of Russia, depending on the weather.
Solar eclipses always follow lunar eclipses, usually about two weeks later.
The United States will have the main show on August 21 for the total solar eclipse -- an event that occurs when the moon passes between Earth and the Sun, thereby blocking out the sunlight and turning day into night for a few minutes.
It will be the first total solar eclipse in 99 years to cross the United States from coast-to-coast, scientists say.
"We're going to be looking at this event with unprecedented eyes," said Alex Young, a solar physicist who is coordinating NASA's education and public outreach.