Astronomers this week are poised for a double show of rare events, but skywatchers in the Pacific and East Asia will have the best view, experts say.
Today will see the first partial lunar eclipse of the year, when Earth slides between the Moon and the Sun, casting a grey shadow over its satellite.
The event runs from 8:48am GMT to 13:18 GMT, according to NASA expert Fred Espenak.
At the greatest point of the eclipse, the southern part of the Moon will seem as if a small bite has been taken out of it.
Weather permitting, most of Australia, all of New Zealand, the nations of the South Pacific and Papua New Guinea will see all of the eclipse, and Southeast Asia, Eastern China, Japan and Korea will get most of it.
It will not be visible in Europe or Africa, but people in western North America and Mexico will see it at the end stages when the moon sets.
Tomorrow, North America will get to see the early stage of the Transit of Venus, one of the most eagerly awaited events in the astronomical calendar.
It occurs when Venus passes between Earth and the Sun, appearing under magnification as a small black dot that trots across the solar face.
The next transit will not take place until 2117.
Australia, New Zealand, the South Pacific, Japan and Korea, as well as most of China and much of Southeast Asia, will be able to see the entire transit, lasting six hours, 40 minutes, on Wednesday morning.
South Asia, the Middle East and Europe will get the end part of the transit, when they enter sunrise on Wednesday.
Anyone viewing the transit should use approved solar filters to prevent damage to the eyes.