By Jesse Emspak /


On the night of May 25-27, observers in Oceania, Hawaii, eastern Asia and Antarctica will see a lunar eclipse that coincides with the moon’s closest approach to Earth — making it a “supermoon” eclipse that will turn the moon reddish — also known as a “blood moon.” (The dates of this eclipse span two days because the area it will be visible spans the international date line). 

Lunar eclipses occur when the moon is on the opposite side of the Earth as the sun. Usually we see a full moon when this happens, but every so often the moon enters the Earth’s shadow, resulting in an eclipse. This doesn’t happen every full moon because the plane of the moon’s orbit is tilted about 5 degrees from the plane of the Earth’s orbit, and the moon “misses” the shadow of the Earth. 

Unlike a solar eclipse, which is only visible along a narrow track, lunar eclipses are visible from the entire night side of the Earth; this entire eclipse takes about five hours from start to finish. The timing depends a lot on what time zone you are in, relative to what is called Universal Coordinated Time (effectively the hour in Greenwich, England). In Asia, the eclipse occurs near moonrise in the evening. On the west coast of the Americas, the eclipse happens in the early morning hours, near moonset. The best viewing will be in between those two extremes: Australia, New Zealand, Hawaii, the islands of the South Pacific and southwestern Alaska. 

This lunar eclipse will appear slightly larger than normal because the moon will reach perigee, the closest point in its orbit to Earth, on May 25 at 9:21 p.m. EDT (0121 May 26 GMT), some 14 hours after it is officially at full phase (which happens at 7:13 a.m. EDT, or 1113 GMT). 

When the full moon and perigee are close, it is called a “supermoon” — though definitions aren’t consistent as it isn’t an astronomical term. Ordinarily the moon is an average of 240,000 miles (384,500 kilometers) from Earth, but its orbit isn’t perfectly circular. So the distance varies slightly. When it reaches perigee this month, the moon will be 222,022 miles (357,311 km) from Earth, per calculations. The moon does appear slightly larger when it is closer, but the difference is small, and it takes a very observant skywatcher to notice. 

The eclipse starts at 4:47:39 a.m. EDT (08:47:39 GMT), according to NASA’s Eclipse Page. That’s when the moon touches the penumbra. The partial phase of the eclipse starts about 57 minutes later, at 5:44 a.m. EDT (09:44:57 GMT). The moon enters the total phase of the eclipse at 7:11:25 EDT (11:11:25 GMT) and completes exiting the umbra at 10:52:22 EDT (12:52:22 GMT). Last contact is at 13:49:41. (To convert from GMT to your time zone you can use this converter). 

In Asia, the westernmost locations to see the eclipse are in India, Sri Lanka, western China and Mongolia, but only the penumbral phase will be visible. In Colombo, Sri Lanka for example, the moon rises at 6:23 p.m. local time on May 26, and the penumbral eclipse ends at 7:19 p.m. local time.

As one moves east more of the eclipse is visible. In Bangkok, the moon — which will already be deep in the Earth’s shadow, appearing reddish — rises at 6:38 p.m. local time and the local maximum eclipse is three minutes later; the moon emerges from the umbra at 7:52 p.m. local time, and the penumbral eclipse ends at 8:49 p.m. local time. 

From Tokyo, one can see the entire umbral phase of the eclipse just after moonrise at 6:37 p.m. local time. The moon will look slightly darker as the penumbral phase will have started already, and the moon touches the umbra at 6:44 p.m. local time. At that point, the moon will be turning red and just peeking over the horizon. The moon will be in the total phase of the eclipse, completely red, at 8:11 p.m. and greatest eclipse is at 8:18 p.m. local time. The total phase ends at 8:25 p.m. and the moon will leave the umbra at 9:52 p.m.; the eclipse ends at 10:49 p.m. local time. 

The eastern two-thirds of Australia will see the entire eclipse. From Melbourne, the penumbral eclipse starts at 6:47 p.m. Australian Eastern Standard Time and the moon is already about 18 degrees above the horizon. The partial phase starts at 7:44 p.m. AEST and the total phase at 9:11 p.m. AEST. At that point, the moon is 45 degrees above the horizon — well above most obstructions. The total eclipse ends at 9:25 p.m. AEST and the umbral phase at 10:52 p.m. AEST. The penumbral phase ends near midnight, at 11:52 p.m. AEST.




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