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Mars near opposition
A global dust storm covers Mars’ disk in this image from the Hubble Space Telescope, captured on July 18. The planet’s two small moons, Deimos (left) and Phobos (right), appear in the lower half of the image. (NASA / ESA / STScI Photo)

It’s no hoax: Mars is bigger and brighter in the night sky than it’s been at any time since 2003. And you can watch the longest total lunar eclipse of the 21st century.

There are caveats, of course: The only way folks in North America can see Friday’s eclipse is to watch it online. And Mars won’t look anywhere near as big as the moon, despite what’s been claimed in a hoax that dates back to, um, 2003.

Nevertheless, this weekend’s astronomical double-header is not to be missed.

Mars and more: Watch the skies

Mars and the moon
Mars is easy to spot low in the southeastern sky in late evening. On the night of the 27th, it will be joined by the full moon. (Sky & Telescope Graphic / Gregg Dinderman)

First, let’s talk about Mars: Due to the alignment of Earth’s 12-month orbit and Mars’ 26-month orbit, there’s wide variation in the distances between the two planets. Mars is just about at its closest when it’s lined up directly opposite the sun, as seen from Earth — a configuration that’s known as opposition.

But even opposition has its variations, because the planets’ orbits are elliptical rather than perfectly circular. This year’s opposition happens to be extraordinarily close — not quite as close as 2003’s 60,000-year record (34.6 million miles), but closer than any opposition since.

And there’s one more twist: The absolutely closest distance this time around won’t come at the precise time of opposition on Friday, when the sun, Earth and Mars are in a perfect line. It’ll come a couple of days later, when the not-quite-circular orbits of Mars and Earth have their closest encounter, known as perigee. At 12:51 a.m. PT on July 31, the distance between Earth and Mars will narrow down to 35,785,537 miles, and then widen again.

The bottom line is that the next few nights are the best times in astronomical terms to be looking at Mars, a bright butterscotch star that rises in the east at sunset, shines directly to the south at midnight and sets at sunrise.

Usually, looking through a telescope will reveal details of Mars’ terrain, including the features that were interpreted as channels or “canals” in the 19th century. Unfortunately, those features are currently obscured due to a global dust storm on the Red Planet. Even so, it’s worth dusting off your binoculars or backyard telescope to try making out the planet’s disk and perhaps its polar caps.

While you’re looking at Mars, don’t miss the rest of the season’s planetary plenitude: Mercury and Venus are relatively close to the sun, but under the right conditions you might be able to catch Venus as a bright gem just after sunset. Jupiter is a little higher up in southwestern skies. Saturn (fresh from its own opposition last month) shines in the southeast at sunset. If you’re up before dawn, there’s even a chance to see Uranus and Neptune.

To get a fix on all the planets, consult the viewing guides at Sky & Telescope or Heavens-Above.com. And then there’s the International Space Station: NASA’s “Spot the Station” website lists nightly opportunities to watch the shining outpost make its way through the sky, customized to your locale.

Lunar eclipse: Watch online

Lunar eclipse
This chart shows which phases of the lunar eclipse will be seen from which parts of the world. P1 marks the start of the penumbral phase, U1 the start of the umbral (partial) phase, U2 the start of totality, U3 the end of totality, U4 the end of the partial phase, and P4 the end of the penumbral phase. North America misses the entire eclipse. (NASA Graphic / Fred Espenak)

Finally, about the moon: For North American observers, the moon stays resolutely in its full phase on Friday night (accompanied by a sparkling Mars, of course). But earlier in the day, the rest of the world will see at least part of an unusually long lunar eclipse. So if you’re in the Western Hemisphere, don’t wait until sunset. Open up your Web browser (or smartphone app) during the daytime and watch the moon turn red online.

The shows get started at 10 a.m. PT when Slooh begins its hosted webcast, focusing on the science behind eclipses and providing views from observing stations. That’s just before the moon enters the penumbral phase of the eclipse, at 10:14 a.m. PT:

Meanwhile, Universe Today and Photographing Space are streaming video from South Africa:

TimeAndDate.com begins its eclipse webcast at 11 a.m. PT:

NASA Television starts streaming live views of the eclipse at about 11:15 a.m. PT, and Earth’s dark shadow starts taking a bite out of the moon’s illuminated disk just minutes later, at 11:24 a.m. PT:

At 11:30 a.m. PT, the Virtual Telescope Project begins webcasting from a particularly picturesque locale: the Roman Forum, on Palatine Hill in Rome, with the Italian capital’s skyline in the background:

The moon turns red (or brown, or gray) at 12:30 p.m. PT when totality begins. Why doesn’t it darken completely? Because some trickles of sunlight are bent as they pass through Earth’s atmosphere, casting a sunset glow on the moon. (Here’s a Flash app I helped put together long ago to explain how lunar eclipses work.)

The Weather Channel will be live-streaming total eclipse imagery for about an hour, starting at 1 p.m. PT, from locales such as Greece, Luxembourg, Italy and Australia. To see that show, you’ll have to use the Weather Channel app.

The eclipse’s total phase ends at 2:13 p.m. PT, and when the partial phase fades out at 3:19 p.m. PT, there’s basically nothing left to do moon-wise except to wait for a glorious Mars-and-moonrise in the evening.

Because of the moon’s position in its orbit around Earth, the eclipse’s total phase will last for 103 minutes, which is nearly the maximum possible duration. That’s the reason why we Americans should be so envious. The next time totality lasts that long will be on June 9, 2123. And the good news about that one is that at least part of that 106-minute stretch of totality will be visible from North America.

Update for 10:20 a.m. PT July 27: We’ve added the Universe Today / Photographing Space live stream.

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