Night Sky, May 2019: What You Can See This Month [Maps]


The night sky tonight and on any clear night offers an ever-changing display of fascinating objects you can see, from stars and constellations to bright planets, often the moon, and sometimes special events like meteor showers. Observing the night sky can be done with no special equipment, although a sky map can be very useful, and a good beginner telescope or binoculars will enhance some experiences and bring some otherwise invisible objects into view. You can also use astronomy accessories to make your observing easier, and use our Satellite Tracker page powered by N2YO.com to find out when to see the International Space Station and other satellites. Below, find out what’s up in the night sky tonight (Planets Visible Now, Moon Phases, Observing Highlights This Month) plus other resources (Skywatching Terms, Night Sky Observing Tips and Further Reading).

The night sky is more than just the moon and stars, if you know when and where to look.
(Image: © Karl Tate/SPACE.com)

Monthly skywatching information is provided to Space.com by Chris Vaughan of Starry Night Education, the leader in space science curriculum solutions. Follow Starry Night on Twitter @StarryNightEdu.

Editor’s note: If you have an amazing skywatching photo you’d like to share for a possible story or image gallery, you can send images and comments in to spacephotos@futurenet.com.

Yearly Night Sky Guides:

When, Where and How to See the Planets in the 2019 Night Sky

The Top Skywatching Events to Look for in 2019

Best Night Sky Events of March’s 2019 (Stargazing Maps) 

Calendar of Observing Highlights

Thursday, May 2 pre-dawn — Old Moon Meets Venus and Mercury

In the eastern pre-dawn sky of Thursday, May 2, the old crescent moon will land 4 degrees to the lower right (south) of bright Venus. At the same time, much dimmer Mercury will be sitting just above the horizon, and 10 degrees to the left of the moon. While the moon and Venus will remain visible until sunrise, Mercury will vanish into the dawn twilight after about 4:30 a.m. local time.

Saturday, May 4 at 22:45 GMT — New Moon

At its new phase, the moon is traveling between the Earth and the Sun. Since sunlight can only reach the side of the moon pointed away from us, and the moon is in the same region of the sky as the sun, the moon is hidden from view for Earth-bound observers. A day or two after new moon, look for the slender sliver of the young crescent moon sitting just above the western horizon after sunset.

Sunday, May 5 pre-dawn — Eta-Aquariid Meteor Shower Peak

The annual Eta-Aquariid Meteor Shower, produced by material from Halley’s Comet, runs from April 19 to May 26 and peaks before dawn on Sunday, May 5. True Aquariids will appear to travel away from a radiant point in Aquarius, near the southeastern horizon. The southerly radiant makes this shower better for observers at low latitudes. Watch for up to a few dozen meteors per hour, including some fireballs, near the peak. The very young evening moon will leave the sky nice and dark for this shower.

Monday, May 6 evening — Moon near Aldebaran

In early evening on Monday, May 6, in the west-northwestern sky, the moon will be positioned above the stars forming Taurus’ triangular face, and that constellation’s brightest star, Aldebaran. Use binoculars (orange circle) to capture the scene. Observers in Europe, Africa, and Asian will see the moon pass through Taurus’ face after dusk.

Tuesday, May 7 early evening — Crescent Moon meets Mars in Taurus

In the western sky on the evening of Tuesday, May 7, the waxing crescent moon will land 3.5 degrees to the lower left (south) of reddish Mars. A medium-bright star named Zeta Tauri (ζ Tauri) will be positioned close to the higher tip of the moon’s crescent. That star marks the eastern horn of Taurus, the Bull.

Friday, May 10 evening — Moon Buzzes the Beehive

In the western sky after dusk on Friday, May 10, the nearly first quarter moon will pass almost directly through the large open star cluster in Cancer known as the Beehive, Praesepe, and Messier 44. The moon will be centered on the cluster at approximately 10 p.m. EDT. Binoculars or a telescope at low magnification (orange circle) will show both the moon and the cluster at the same time. To better see the clusters’ stars, try to position the moon just outside of your optics’ field of view. 

Sunday, May 12 at 1:12 GMT — First Quarter Moon

At first quarter, the relative positions of the Earth, sun, and moon cause us to see the moon half illuminated — on the eastern (right-hand) side. First quarter moons rise around noon and set around midnight, so they are visible starting in the afternoon hours. The term quarter moon refers not to its appearance, but the fact that our natural satellite has now completed the first quarter of its orbit around Earth since the last new moon.

Saturday, May 18 pre-dawn — Venus Passes Uranus

On Saturday, May 18, Venus’ rapid orbital motion toward the sun (red curve) will carry it past distant Uranus. The two planets will sit low over the east-northeastern horizon before dawn, making dim Uranus difficult to see.

Saturday, May 18 at 21:11 GMT — Full Milk Moon

The May full moon, known as the Full Milk Moon, Full Flower Moon, or Full Corn Planting Moon, always shines in or near the stars of Libra. Full moons always rise in the east as the sun sets, and set in the west at sunrise. Since no shadows are cast by the vertically impinging sunlight on a full moon, all of the brightness differences are generated by the reflectivity, or albedo, of the surface geology. This year we celebrate the 50th anniversary of the first footsteps by humans on the moon.

Sunday, May 19 evening — Mars Attacks Messier 35

In the north-northwestern sky on the evening of Sunday, May 19, the reddish planet Mars will be positioned only 0.25 degrees (or half the full moon’s diameter) above (northeast) of the prominent open star cluster known as Messier 35 and NGC 2168. Mars and the star cluster’s many stars will all fit together into the field of view of a backyard telescope at medium magnification (red circle). (Your optics might flip and/or invert the view.) Binoculars will also show this cluster under moderately dark skies. Look for another, dimmer open cluster designated NGC 2158 sitting below M35.

Sunday, May 19 overnight — Gibbous Moon moves with Jupiter

When the waning gibbous moon rises from the southeastern horizon after 10 p.m. local time on Sunday, May 19, it will be positioned only 7 degrees to the upper right (west) of bright Jupiter. As the pair crosses the night sky together, the moon’s orbital motion (red line) will carry it noticeably closer to Jupiter. The pairing will remain visible until just before sunrise, at which time, they will be over the south-western horizon.

Tuesday, May 21 overnight — Gibbous Moon moves with Saturn

For the second time this week, the waning gibbous moon will cross the sky with a bright planet. When the waning gibbous moon rises from the southeastern horizon after 11 p.m. local time on Tuesday, May 21, it will be positioned 9 degrees to the upper right (west) of yellowish Saturn. As the pair crosses the night sky, the moon’s orbital motion (red line) will carry it noticeably closer to Saturn. They will remain visible until about 4 a.m. local time, at which time they will sit in the southern sky. Observers in the southern tip of Africa, parts of eastern Antarctica, Kerguelen Islands, most of Australia, and southern New Zealand will see the moon occult the Ringed Planet. 

Sunday, May 26 at 16:34 GMT — Last Quarter Moon

At its last quarter phase, the moon rises around midnight and remains visible in the southern sky during morning daylight. At this time, the moon is illuminated on the western (left-hand) side, towards the pre-dawn Sun. Last quarter moons are positioned ahead of the Earth in our trip around the Sun. About 3½ hours later, earth will occupy that same location in space. After this phase, the waning moon traverses the last quarter of its orbit around the earth, on the way to new moon.

Tuesday, May 28 all night — Ceres at Opposition

On Tuesday, May 28, the dwarf planet (formerly asteroid) Ceres will reach opposition, its closest approach to Earth for the year. Its path over several months is indicated in red, with dates. On the nights around opposition, Ceres will shine with a peak visual magnitude of 7.1, well within reach of binoculars and backyard telescopes. As a bonus, Ceres will be situated only 1 degree to the upper right of the naked-eye star Xi Ophiuchi. Both objects will easily fit within the field of view of a backyard telescope (orange circle), although your telescope will mirror and/or invert the inset view shown. Located less than 9 degrees above the bright, orange star Antares, Ceres will already be climbing the southeastern sky after dusk. It will reach its highest elevation, and peak visibility, over the southern horizon at midnight local time.

Planets

During the opening days of May, Mercury will complete a so-so morning apparition for Northern Hemisphere observers (and a very good one for southerners), remaining in view low over the eastern pre-dawn sky until mid-month while it swings sunward and dips into the morning twilight. At the same time, the planet will brighten as its illuminated phase increases from waxing gibbous to full. Superior conjunction with the sun will occur on May 21. After conjunction, the swift planet will join the eastern evening sky to begin a lengthy evening apparition that will offer good observing opportunities from the Northern Hemisphere. On May 2, the old crescent moon will be positioned 10 degrees to the right of Mercury. The following morning, the moon will land 3 degrees below the Mercury.

Venus will spend the entirety of May positioned low in the eastern pre-dawn sky among the stars of first Pisces and then Aries. Venus will remain embedded within the morning twilight while it slowly decreases its angular separation from the sun. During this period, the extremely bright planet will shine at magnitude -3.8 and exhibit a nearly fully illuminated phase. Its disk will slightly decrease in apparent diameter from 11.5 to 10.5 arc-seconds as it recedes from Earth. On May 2, the old crescent moon will land 4 degrees to the lower right (south) of Venus. On May 18, Venus will pass one degree south of Uranus – but that distant, dim planet will be very hard to observe.

Reddish Mars will spend May in the western early evening sky, decreasing its angular separation from the sun from 40 degrees to 30 degrees and reducing its viability as an observing target. Mars’ easterly prograde motion will carry it from the stars of Taurus and into Gemini on May 16. During the course of May, Earth’s orbital motion will continue to increase our distance from the Red Planet. As a result, Mars will diminish in brightness (from visual magnitude 1.64 to 1.76) and its apparent disk diameter will decrease from 4.2 to 3.9 arc-seconds. On the evening of May 7, the waxing crescent moon will land 3.5 degrees to the lower left (south) of Mars. On May 18, Mars will pass less than 0.5 degrees to the right (north) of the prominent open star cluster known as Messier 35 (NGC 2168). The following night, Mars will move to sit 0.3 degrees above that cluster. Both objects will appear together in the field of view of a medium power telescope.

Jupiter, which began to rise just before midnight in late April, will gradually move into a convenient position for evening observing in the southeastern sky during May. By the end of the month, the bright magnitude -2.5 planet will be rising at about 9:30 p.m. local time. Throughout May, Jupiter will be moving retrograde westward through the stars of southern Ophiuchus. In the post-midnight sky on May 19, the waning gibbous moon will be positioned only 7 degrees to the upper right (west) of bright Jupiter. As the pair crosses the night sky together, the moon’s orbital motion will carry it noticeably closer to Jupiter. On the following night, the moon will jump to a position to Jupiter’s lower left (east). Watch for occasional transits of the round, black shadows cast upon Jupiter by its four large Galilean moons.

Saturn will spend May as a medium bright, yellowish object moving retrograde through the northeastern part of Sagittarius. In early May, the ringed planet will rise in the east after 1:30 a.m. local time and remain visible until dawn, when it will be culminating 24 degrees above the southern horizon. During the closing days of the month, Saturn will begin to rise just before midnight local time. Meanwhile, the planet will slightly brighten and grow larger in apparent size as Earth moves closer to it ahead of opposition in July. When the waning gibbous moon rises from the southeastern horizon after 11 p.m. local time on May 21, it will be positioned 9 degrees to the upper right (west) of Saturn. As the pair crosses the night sky, the moon’s orbital motion will carry it noticeably closer to Saturn. Observers in the southern tip of Africa, parts of eastern Antarctica, Kerguelen Islands, most of Australia, and southern New Zealand will see the moon occult the Ringed Planet.

During May, blue-green Uranus (magnitude 5.89) will be in the pre-dawn sky among the stars of southwestern Aries, but it will not be readily observable until late in the month when it will begin to rise in a dark sky before 4:30 a.m. local time. On May 18, Venus’ rapid orbital motion toward the sun will carry it one degree to the lower right (south) of Uranus. The two planets will sit low over the east-northeastern horizon before just dawn, making dim Uranus difficult to see.

Blue-tinted Neptune (magnitude 7.9) will spend May in the eastern pre-dawn sky among the stars of Aquarius. As the month wears on, the planet will rise earlier, increasing the window of time for observing it in telescopes before the onset of morning twilight.

Skywatching Terms

Gibbous: Used to describe a planet or moon that is more than 50 percent illuminated.

Asterism: A noteworthy or striking pattern of stars within a larger constellation.

Degrees (measuring the sky): The sky is 360 degrees all the way around, which means roughly 180 degrees from horizon to horizon. It’s easy to measure distances between objects: Your fist on an outstretched arm covers about 10 degrees of sky, while a finger covers about one degree.

Visual Magnitude: This is the astronomer’s scale for measuring the brightness of objects in the sky. The dimmest object visible in the night sky under perfectly dark conditions is about magnitude 6.5. Brighter stars are magnitude 2 or 1. The brightest objects get negative numbers. Venus can be as bright as magnitude minus 4.9. The full moon is minus 12.7 and the sun is minus 26.8.

Terminator: The boundary on the moon between sunlight and shadow.

Zenith: The point in the sky directly overhead.

Night Sky Observing TipsAdjust to the dark: If you wish to observe faint objects, such as meteors or dim stars, give your eyes at least 15 minutes to adjust to the darkness.Light Pollution: Even from a big city, one can see the moon, a handful of bright stars and sometimes the brightest planets. But to fully enjoy the heavens — especially a meteor shower, the constellations, or to see the amazing swath across the sky that represents our view toward the center of the Milky Way Galaxy — rural areas are best for night sky viewing. If you’re stuck in a city or suburban area, a building can be used to block ambient light (or moonlight) to help reveal fainter objects. If you’re in the suburbs, simply turning off outdoor lights can help.Prepare for skywatching: If you plan to be out for more than a few minutes, and it’s not a warm summer evening, dress warmer than you think necessary. An hour of observing a winter meteor shower can chill you to the bone. A blanket or lounge chair will prove much more comfortable than standing or sitting in a chair and craning your neck to see overhead.Daytime skywatching: When Venus is visible (that is, not in front of or behind the sun) it can often be spotted during the day. But you’ll need to know where to look. A sky map is helpful. When the sun has large sunspots, they can be seen without a telescope. However, it’s unsafe to look at the sun without protective eyewear. See our video on how to safely observe the sun, or our safe sunwatching infographic.Further Reading

Moon Phases: How the lunar cycle works, from full moon to new moon. Also find out when is the next full moon.

Constellations: The history of the Zodiac constellations and their place in night sky observing.

Lunar Eclipses: How they work, plus find out when’s the next lunar eclipse.

Solar Eclipses: How they work, the types, and when the next one occurs.

Source: space.com

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