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Moon, Uranus in Pisces on February 19

Tonight – February 19, 2018 – finds the evening crescent moon and the planet Uranus in front of the constellation Pisces the Fishes. Uranus, the 7th planet outward from the sun, was the first the planet to be discovered by the telescope. With Sir William Herschel’s discovery of Uranus in 1781, Saturn no longer marked the outermost point of the solar system. All of a sudden, the diameter of the known solar system doubled from 10 to 20 astronomical units.

But don’t expect to see Uranus tonight with the naked eye. On a dark, moonless night, people with extraordinary vision can sometimes spot Uranus as a faint speck of light. But you can spot Uranus with binoculars if you know right where to look. That’s when a good familiarity with the constellation Pisces and a detailed sky chart come in handy. Find the faint 4th-magnitude star Omicron Piscium, which is visible to the unaided eye in a dark sky, and then seek for the planet Uranus in the same binocular field with Omicron Piscium.

Sky chart of the constellation Pisces via the IAU. We list the star Omicron Piscium. for a sky chart.

Uranus is a mighty gas or ice giant planet in the outer solar system. It is much, much larger than our moon. Neptune only appears small and faint because of the planet’s much greater distance from Earth. Uranus resides about 20.5 astronomical units away from Earth. That’s nearly 8,000 times farther than tonight’s moon.

You’ll find some useful charts on these pages:

Uranus and Neptune through March 2018, from SkyandTelescope.com

Path of Uranus till January 2019, from NakedEyePlanets.com

Uranus information on The Sky Live

Although Uranus looks like a faint star, even through binoculars, that's only because this distant world resides in the outskirts of the planetary system, at about  19 AU from the sun. Uranus' diameter is actually four times greater than Earth's diameter, and its surface area some 16 times greater than that of Earth.

Although Uranus looks like a faint star, even through binoculars, that’s only because this distant world resides in the outskirts of the planetary system, at nearly 20 AU from the sun. Uranus’ diameter is actually four times greater than Earth’s diameter, and its surface area some 16 times greater than that of Earth.

The moon will pass out of constellation Pisces and into the constellation Aries after a day or two. But Uranus won’t move into Aries until May 2018, at which time Uranus will have moved into the morning sky.

For the next few nights – February 19 and 20 – the waxing crescent moon shows you the approximate position of planet Uranus on the sky’s dome.

Bruce McClure

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Keep watching for Leonid meteors

Between midnight and dawn on Saturday, November 18, watch for meteors in the annual Leonid meteor shower. Maybe you saw some meteors on the morning of November 17, too? In 2017, the peak stretches over two mornings, and a new moon on November 18 guarantees darkness (from rural locations) on both nights.

The Leonids are famous for storming at various times in recent history. The first great meteor storm of modern times was nearly 200 years ago; it was the Leonid shower of November 1833. That famous shower had a major effect on the development of the scientific study of meteors. It’s one reason the Leonids are so famous.

Previously, meteors were thought to be atmospheric phenomena, like rain or snow. But scientists were curious. Why was the 1833 shower so strong? In 1865, astronomers discovered a comet, which was named Comet Tempel-Tuttle for its discoverers. The comet’s orbit around the sun was found to be about 33 years. Some predicted that there would be another Leonid meteor storm in November 1866 – and so there was!

Thus the Leonid meteor storm of 1833 helped prove that meteors in annual shower originate in comets.

Leonid meteor storm, as seen over North America on the night of November 12-13, 1833. This woodcut was published in 1888 by E. Weib in his Bilderatlas der Sternenwelt (Illustrated Atlas of the Stars). Image via Wikimedia Commons.

Now we know that Earth crosses the orbital path of Comet Tempel-Tuttle every year. Debris from this comet burns up in the Earth’s upper atmosphere to create the annual Leonid shower. It’s only when the comet is near that we see a Leonid storm.

The illustration above depicts the 1833 Leonid meteor shower, said to have produced from 100,000 to 200,000 meteors per hour! This old woodcut, published in 1888, shows what the Leonid shower might look like in a year that this shower erupts into storm, bombarding the sky with hundreds of thousands of meteors.

That happened last in 1966, when North Americans enjoyed a Leonid storm numbering 100,000 shooting stars per hour. Since then, the Leonids have put on some stunning displays, but nothing to match the 1966 shower.

Will there be a Leonid storm in 2017? That’s one prediction we can make with a fair amount of certainty, and the answer is no. No storm or heightened meteor activity is anticipated for the Leonid meteor shower in 2017. That’s because the parent comet of the Leonid shower is not nearby.

The comet takes just over 33 years to orbit the sun. Its last perihelion (closest point to the sun) was February 28, 1998. Its next expected perihelion is May 20, 2031. So we’ve got awhile to wait for the next Leonid storm!

When they’re not storming, the Leonids are a modest, though reliable, shower. In a dark, moonless sky, you might see up to 10 to 15 meteors per hour. The absence of moonlight will undoubtedly enhance the view of this shower in 2017.

Even watching just one meteor flying across the sky can count as a big thrill. A good percentage of these swift-moving meteor leave persistent trains – glowing trails of ionized gas that last for a few moments are the meteor has gone!

On a dark night, we typically see the most Leonid meteors streaking the sky in the hour before before dawn because that’s when the constellation Leo the Lion – the radiant point of the shower – is found highest in the sky. In 2017, those wanting to make a night of it can observe Mars rising in the east around 3 a.m. local time, and then Jupiter and Venus coming up as the predawn darkness gives way to morning twilight. Click here for an almanac telling you when these planets will rise into your sky.

The planetary line-up shortly before sunrise November 18, 2017. Mars and Spica rise before dawn. Jupiter rises just as the predawn darkness is beginning to give way to morning twilight. Venus rises after dawn’s first light. Click here for an almanac.

Many ask about the radiant points of meteor showers. Please know that you don’t have to locate the radiant point to watch the Leonid shower, for these meteors fly all through the starry heavens. But it’s fun to know where the radiant lies in the sky. When tracing the paths of the Leonid meteors backward, they appear to radiate from the constellation Leo the Lion. Therefore, the meteors in this annual shower are named for this constellation. As seen from mid-northern latitudes, Leo rises over eastern horizon around 1 a.m. After rising, Leo then climbs upward and westward, soaring to its highest point in the southern sky around 6:30 a.m. local time.

Bottom line: On the night of November 17-18, find a dark sky away from pesky artificial lights, enjoy the comfort of a reclining lawn chair and sleeping bag, and enjoy watching the swift-moving and often bright Leonid meteor shower. The new moon on November 18 guarantees a dark sky.

Never miss another full moon. Order your 2017 EarthSky moon calendar today! Supplies limited.

How high up are meteors when they begin to glow?

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Bruce McClure

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