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May guide to the bright planets

Three of the 5 bright planets are easy to see: Jupiter, Saturn and Venus. Mars is obscured in western twilight. Mercury is up there, too, but veiled by eastern dawn.

Watch for the waning crescent moon to swing by Venus on the mornings of May 21, 22 and 23. Read more.

Three of the 5 five bright planets are easy to see in the May 2017 night sky: Jupiter, Saturn and Venus. Jupiter appears first thing at dusk and shines nearly all night long. Saturn rises into the southeast sky at mid-to-late evening and then stays out for rest of the night. Venus rises over the eastern horizon as the predawn darkness is giving way to morning dawn. Mars and Mercury present more of a challenge this month, as Mars is somewhat obscured by evening dusk and Mercury by morning dawn. Follow the links below to learn more about the planets in May 2017.

Mercury, below Venus, low in east before sunrise

Mars fading into western evening twilight

Bright Jupiter rules the nighttime

Saturn from late evening till dawn

Venus, brilliant in east at morning dawn

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Wow! Wonderful shot of Mercury – over the Chilean Andes – January 2017, from Yuri Beletsky Nightscapes.

From northerly latitudes, Mercury is found to the lower left of the brilliant planet Venus. From the Southern Hemisphere, look for Mercury about the same distance from Venus but more directly below. Read more.

Mercury, below Venus, low in east before sunrise. When we say that Mercury is low in the east before sunrise, we’re really talking about the Northern Hemisphere. For the Southern Hemisphere, May 2017 presents the best showing of Mercury in the morning sky for the year. (For northerly latitudes, this is least favorable apparition of Mercury in the morning sky in 2017.) For much of the Southern Hemisphere, Mercury actually comes up before dawn’s first light all month long; in the Northern Hemisphere, Mercury rises a short while before sunrise and sits low in the glare of morning twilight throughout May 2017.

Mercury is tricky. If you look too soon before sunrise, Mercury will still be below the horizon; if you look too late, it will obscured by the morning twilight. Watch for Mercury low in the sky, and near the sunrise point on the horizon, being mindful of Mercury’s rising time.

Binoculars are always helpful for any Mercury search. Use them to scan along the eastern horizon until a starlike point – deep in the twilight – comes into view. Mercury is bright, but it’s always near the sunset or sunrise. Thus you have to search for it.

If you live in the Southern Hemisphere, this is your month! A super apparition of Mercury take places in the morning sky throughout May of 2017.

Watch for the slender waning crescent moon to pair up with Mercury on or near May 23.

Click here for recommended almanacs; they can give you Mercury’s rising time in your sky.

Let the young moon guide you to Mars’ place in the sky on May 26 and 27. You may need binoculars to see Mars in the glare of evening twilight. Read more.

Mars fading into western evening twilight. After appearing as a fiery red light last year – in May and June 2016 – Mars is now a fading ember of its former self. Look for Mars rather low in the west as soon as darkness begins to fall. Mars is edging closer to the sunset day by day. It’ll disappear in the glare of evening dusk by June 2017.

Because Earth is traveling faster in its orbit than Mars is, Earth’s distance from Mars is increasing by the day. So there are two reasons for Mars’ disappearing act this month. Its increasing distance from Earth means Mars’ brightness is decreasing daily. Plus, Mars is setting sooner after the sun with each passing day. The fading planet is sinking closer to glare of sunset, soon to disappear from the evening sky.

From mid-northern latitudes (U.S. and Europe), look for the red planet Mars to set in the west around nightfall in early May, and a bit more than one hour after sunset by the month’s end. The same holds true for mid-southern latitudes (Australia and South Africa).

Let the waxing crescent moon help guide you to Mars on May 26. This will probably be your last chance to catch the young waxing crescent moon and Mars coupling up together in the evening sky this year. You may need binoculars to see Mars in the glow of evening dusk.

Mars won’t make its official transition from the evening to morning sky until July 27, 2017. It’ll emerge in the east before dawn in late September or October 2017. The conjunction of Mars and Venus on October 5, 2017, might well be the first time most people notice the red planet in the morning sky.

Looking for a sky almanac? EarthSky recommends…

Look for the bright waxing gibbous moon to beam close to Jupiter on May, 6, 7 and 8. Read more.

Bright Jupiter rules the nighttime. Jupiter reached opposition on April 7 and came closest to Earth for the year on April 8. Although Jupiter shone at its brightest best for all of 2017 in April, it’ll still be blazing away in May! Jupiter beams as the third-brightest celestial body in the nighttime sky, after the moon and Venus. Yet Jupiter shines from dusk until the wee hours of the morning whereas Venus only appears in the morning sky. In fact, this month will find Jupiter setting in the west at roughly the same time that Venus rises in the east.

Click here for an almanac telling you Jupiter’s setting time and Venus’ rising time in your sky.

Watch for a bright waxing gibbous moon to join up with Jupiter for several days, centered on or near May 6. See the above sky chart. Wonderful sight!

From around the world, Jupiter appears in the east to southeast sky first thing at dusk. It crosses the sky during the night, to set in the west to southwest at or near dawn.

Jupiter shines in front of the constellation Virgo, near Virgo’s sole 1st-magnitude star, Spica.

Fernando Roquel Torres in Caguas, Puerto Rico captured Jupiter, the Great Red Spot (GRS) and all 4 of its largest moons – the Galilean satellites – on the date of Jupiter’s 2017 opposition (April 7).

If you have binoculars or a telescope, it’s fairly easy to see Jupiter’s four major moons, which look like pinpricks of light on or near the same plane. They are often called the Galilean moons to honor Galileo, who discovered these great Jovian moons in 1610. In their order from Jupiter, these moons are Io, Europa, Ganymede and Callisto.

These moons circle Jupiter around the Jovian equator. In cycles of six years, we view Jupiter’s equator edge-on. So, in 2015, we got to view a number of mutual events involving Jupiter’s moons through a high-powered telescope. Click here or here or here for more details.

Although Jupiter’s axial tilt is only 3o out of perpendicular relative to the ecliptic (Earth’s orbital plane), Jupiter’s axis will tilt enough toward the sun and Earth so that the farthest of these four moons, Callisto, won’t pass in front of Jupiter or behind Jupiter for a period of about three years, starting in late 2016. During this approximate 3-year period, Callisto will remain “perpetually” visible, alternately swinging “above” and “below” Jupiter.

Click here for a Jupiter’s moons almanac, courtesy of Sky & Telescope.

Watch for the waning gibbous moon to pass close to the star Antares and the planet Saturn on May 11, 12 and 13. Read more.

Saturn from late evening till dawn. Saturn is getting close to its June 15 opposition and is now appearing the evening sky.

From mid-northern latitudes, Saturn rises in the southeast sky somewhere around 10 to 11 p.m. local time (11 p.m. to midnight daylight-saving time) in early May 2017. By the month’s end, Saturn is up by late dusk or nightfall.

At temperate latitudes in the Southern Hemisphere, Saturn rises around mid-evening (8:30 to 9:30 p.m. local time), and by the month’s end, Saturn rises at late dusk or nightfall.

But your best view of Saturn, from either the Northern or Southern Hemisphere, is still during the wee hours before dawn. That’s when Saturn climbs highest up for the night. Click here to find out Saturn’s transit time (when Saturn soars highest up for the night).

Be sure to let the waning crescent moon guide you to Saturn (and the nearby star Antares) for several days, centered on or near May 13.

Saturn, the farthest world that you can easily view with the eye alone, appears golden in color. It shines with a steady light.

Binoculars don’t reveal Saturn’s gorgeous rings, by the way, although binoculars will enhance Saturn’s golden color. To see the rings, you need a small telescope. A telescope will also reveal one or more of Saturn’s many moons, most notably Titan.

Saturn’s rings are inclined at nearly 27o from edge-on, exhibiting their northern face. In October 2017, the rings will open most widely, displaying a maximum inclination of 27o.

As with so much in space (and on Earth), the appearance of Saturn’s rings from Earth is cyclical. In the year 2025, the rings will appear edge-on as seen from Earth. After that, we’ll begin to see the south side of Saturn’s rings, to increase to a maximum inclination of 27o by May 2032.

Click here for recommended almanacs; they can help you know when the planets rise, transit and set in your sky.

Jenney Disimon in Sabah, Borneo captured Venus before dawn on April 8, 2017.

Watch for the waning crescent moon to swing by Venus on the mornings of May 21, 22 and 23. Read more.

Venus, brilliant in east at morning dawn In the first three weeks of March 2017, Venus shone in the west after sunset. In late March, Venus entered our morning sky, passing between the sun and Earth on March 25. Venus then reached its greatest illuminated extent in the morning sky on April 30. This dazzling world will still be at or near its peak brilliance as the morning “star” in early May 2017.

So it’s brightest in the morning sky in late April and early May, but … Venus is always brilliant and beautiful, the brightest celestial body to light up our sky besides the sun and moon. If you’re an early bird, you can count on Venus to be your morning companion for many months to come.

Enjoy the picturesque coupling of the waning crescent moon and Venus in the eastern sky before sunrise on or near May 22.

From mid-northern latitudes (U.S. and Europe), Venus rises nearly two hours before sunrise in early May, and by the month’s end, Venus comes up a little more than two hours before the sun.

At mid-southern latitudes (Australia and South Africa), Venus rises about about 3 hours before sunup in early May, and by the end of the month, it comes up nearly 4 hours before sunrise. Venus and Mercury both rise much sooner before the sun in the Southern Hemisphere than they do in the Northern Hemisphere.

Click here for an almanac giving rising time of Venus and Mercury in your sky.

The chart below helps to illustrate why we sometimes see Venus in the evening, and sometimes before dawn.

Earth's and Venus' orbits

The Earth and Venus orbit the sun counterclockwise as seen from earthly north. When Venus is to the east (left) of the Earth-sun line, we see Venus as an evening “star” in the west after sunset. After Venus reaches its inferior conjunction, Venus then moves to the west (right) of the Earth-sun line, appearing as a morning “star” in the east before sunrise.

This month, Jupiter will set in the west at roughly the same time that Venus rises in the east. Next month, in June, Jupiter will set in the west before Venus rises in the east.

What do we mean by bright planet? By bright planet, we mean any solar system planet that is easily visible without an optical aid and that has been watched by our ancestors since time immemorial. In their outward order from the sun, the five bright planets are Mercury, Venus, Mars, Jupiter and Saturn. These planets actually do appear bright in our sky. They are typically as bright as – or brighter than – the brightest stars. Plus, these relatively nearby worlds tend to shine with a steadier light than the distant, twinkling stars. You can spot them, and come to know them as faithful friends, if you try.

From late January, and through mid-February, 5 bright planets were visible at once in the predawn sky. This image is from February 8, 2016.  It's by Eliot Herman in Tucson, Arizona.  View on Flickr.

This image is from February 8, 2016. It shows all 5 bright planets at once. Photo by our friend Eliot Herman in Tucson, Arizona.

Skywatcher, by Predrag Agatonovic.

Skywatcher, by Predrag Agatonovic.

Bottom line: In May 2017, three of the five bright planets appear in the evening sky: Mars, Jupiter and Saturn. Venus and Mercury are found exclusively in the morning sky.

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Bruce McClure