The first of two lunar eclipses in 2017 occurs overnight on Friday and Saturday (Feb. 10 and 11), when the full moon passes through the outer shadow of the Earth. The event is a minor eclipse known as a penumbral lunar eclipse. You can see our main guide here: February Full Moon 2017: When to See the 'Snow Moon' Eclipse
During a total lunar eclipse, skywatchers can often see the moon turn an intense, blood-red color as it passes through the central shadow of the Earth. But during a penumbral eclipse, like the one happening this week, sunlight is only blocked by the outer shadow of the Earth, called the penumbra. The Slooh Community Observatory will offer a live webcast of the eclipse at Slooh.com on Feb. 10 beginning at 5:30 p.m. EST (2230 GMT). You can also watch the lunar eclipse webcast on Space.com, courtesy of Slooh.
The February lunar eclipse is one of several minor lunar eclipses leading to the next total eclipse of the moon in early 2018. [Lunar Eclipses: What Are They & When Is the Next One?]
Looking out for a penumbral eclipse
Penumbral eclipses can be difficult to see from Earth because the moon is merely passing through the Earth's penumbral shadow, causing only subtle shading on the moon's surface.
"The outer part of Earth's penumbra is so pale that you won’t notice anything until the moon's edge has slid at least halfway in," Alan MacRobert, a senior editor at Sky & Telescope magazine, said in a statement. "So start looking about 90 minutes before mid-eclipse," when the eclipse is at its maximum. For the Feb. 10 lunar eclipse, that halfway mark occurs at 7:44 p.m. EST on Friday night (0044 Saturday, Feb. 11 GMT).
To an observer on the surface of the moon, however, during a penumbral eclipse the Earth would appear to be partially eclipsing the sun. This can have a more significant impact on scientific operations like NASA's Lunar Reconnaissance Orbiter (LRO), a spacecraft that orbits the moon. Even a minor lunar eclipse is important for LRO mission scientists to keep tabs on.
"Because our spacecraft gets its power from the sun, when the sun disappears we have to be aware of that," Noah Petro, a research scientist at the Goddard Space Flight Center in Maryland who is part of the LRO team, has said of past penumbral lunar eclipses.
The Feb. 10-11 penumbral eclipse, though subtle, will best be visible to varying degrees across North and South America, Europe, Africa, and Asia. As mentioned above, the point of maximum eclipse will take place at 7:44 p.m. EST (0044 GMT). That means observers in northeastern United States and eastern Canada will be well-placed to see the eclipse at its peak.
During a solar eclipse, if you aren't along the path of totality you might miss the event altogether. Unlike solar eclipses, lunar eclipses are visible from a much wider spectrum and for a slightly longer period of time — up to 10 minutes, where solar eclipses might last 7 minutes at most. The Feb. 10-11 penumbral lunar eclipse will last 4.5 hours from start to finish. Sky & Telescope's MacRobert suggests to begin observing the moon about 90 minutes BEFORE peak eclipse time at 7:44 p.m. EST (0044 GMT) to make the most of your observing time.
What do you need to see it?
It's going to be somewhat of a challenge to see the penumbral eclipse without help from a telescope. But before bothering with equipment, skywatchers will first have to worry about geography.
"The first thing is to make sure that it'll be visible wherever you are," Petro said. "While these lunar eclipses are more forgiving and you don't have to be along the path of totality, you do have to be in the right hemisphere to see it."
For best viewing, rely on a basic telescope or even a good pair of binoculars. A standard DSLR camera should capture an image without a hitch. During partial and total eclipses in which the moon passes into the central shadow of the Earth (the umbra), you might not even need equipment to see the moon's surface change to an orange or even deep-red color, something that Petro suggests everyone should make an effort to see.
When is the next lunar eclipse?
There will be a partial lunar eclipse on Aug. 7, 2017 and will peak at 2:20 p.m. EST (1920 GMT). The eclipse will be visible to observers in Africa, Europe, Australia and much of eastern Asia. The big lunar event, a total lunar eclipse, will take place Jan. 31, 2018, and will be visible across Asia, Australia, the Pacific, and parts of the Western U.S.
According to Petro, the 2018 total lunar eclipse will be a much more obvious skywatching event, and will require the LRO to turn off all but one of the instruments aboard the orbiter.
"We can get really good science out of what happens to the surface of the moon during total lunar eclipses but again, the cool thing is that the moon changes color," Petro said. "It's something fun to see — it's benign, but it's a change. And anytime we see change in the skies it's always kind of exciting."
Editor's note: If you capture an amazing photo of the penumbral lunar eclipse and want to share it with Space.com for a story or gallery, send images and comments in to managing editor Tariq Malik at firstname.lastname@example.org.