Night Sky, July 2018: What You Can See This Month [Maps] | Innovation Tech
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).
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, please contact managing editor Tariq Malik at firstname.lastname@example.org.
Yearly Night Sky Guides:
When, Where and How to See the Planets in the 2018 Night Sky
The Top Skywatching Events to Look for in 2018
Best Night Sky Events of June 2018 (Stargazing Maps)
Calendar of Observing Highlights
Tuesday, July 3 after dusk – Mercury Buzzes the Beehive Cluster
On the evening of Tuesday, July 3, Mercury’s orbital motion will carry it through the southern edge of the Beehive Cluster (also known as Messier 44) in Cancer. Look for the pairing a few degrees above the western horizon, especially between about 10 and 10:15 p.m. local time. Binoculars (orange circle) or a small telescope should pull some of the cluster’s brighter stars out of the twilight sky. The following evening, Mercury’s position will be east (left) of the cluster.
Friday, July 6 at 3:51 a.m. EDT – Last Quarter Moon
At its last quarter phase, the moon rises around midnight and remains visible in the southern sky all morning. At this phase, the moon is illuminated on its western 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.
Friday, July 6 at 1 p.m. EDT – Earth at Aphelion
On Friday, July 6, Earth will reach aphelion, its maximum distance from the sun for this year. The aphelion distance of 94,507,803 miles (152,095,566 km) is 1.67 percent farther from the sun than the mean Earth-sun separation of 92,955,807.3 miles (149,597,870.7 km), which is also known as 1 Astronomical Unit (AU). Earth’s perihelion (minimum distance from the sun) will occur on January 3. At that time, the sun will be 91,401,983 miles (147,097,233 km) from Earth.
Sunday, July 8 from 9:37 to 10:37 p.m. EDT – Io and its Shadow Transit Jupiter
From time to time, the little round shadows cast by Jupiter’s four Galilean moons become visible in backyard telescopes as they cross (or transit) the planet’s disk. On Sunday, July 8 from 9:37 to 10:37 p.m. EDT, Io and its shadow will transit Jupiter. After Io moves off the planet, the shadow will linger until 11:46 p.m.
Monday, July 9 evening – Venus meets Regulus
In the western sky on the evening of Monday, July 9, Venus’ orbital motion (purple line) will carry it only 1 degree north (to the upper right) of Leo’s brightest star Regulus. The pair of objects will easily fit within the field of view of binoculars (orange circle). They will set shortly after 11 p.m. local time. Because Regulus is located less than 0.5 degree north of the ecliptic, it frequently has encounters with the moon and planets.
Tuesday, July 10 pre-dawn – Aldebaran Encounters the Old Moon
In the eastern pre-dawn sky on July 10, the eastward orbital motion of the waning crescent moon will carry it just above reddish Aldebaran, the brightest star in Taurus. Observers in Central America, northern North America, most of Greenland, and north-central Russia will see the moon pass in front of (or occult) the star. Observers just south of those regions will see the star graze the moon’s dark southern limb, and the rest of the world will see the two objects somewhat farther apart, but the pair will still fit within the field of view of a telescope at low magnification (orange circle).
Tuesday, July 10 all night – Jupiter Stands Still
On Tuesday, July 10, Jupiter will cease its motion through the distant stars as it completes a retrograde loop that began in early March. After tonight, the king of planets will resume its regular eastward orbital motion. By watching Jupiter’s separation from the nearby bright double star Zubenelgenubi over days or weeks, the planet’s motion (red line) will be apparent. Retrograde loops are produced when Earth’s faster motion overtakes planets that orbit farther from the sun than Earth.
Thursday, July 12 after sunset – Mercury at Greatest Eastern Elongation
In the early hours of Thursday, July 12, Mercury will officially reach its widest separation east of the Sun. Viewed in a telescope on the previous evening (inset), the planet will exhibit a waning illuminated phase of 41 percent. While the elusive inner planet will be separated from the sun by 26 degrees, the shallow dipping evening ecliptic will cause Mercury to set soon after sunset, making this a poor apparition for Northern Hemisphere observers (but a good one for Southern Hemisphere viewers). The best period to look for Mercury falls between 9:30 and 10 p.m. local time.
Thursday, July 12 all night – Pluto at Opposition
On Thursday, July 12, the dim and distant dwarf planet Pluto will reach opposition, the day of the year when Earth moves between the planet and the sun. On this date, Pluto will be the closest to Earth (3.03 billion miles, 4.87 billion km, or 271 light-minutes) and brightest (visual magnitude +14.2) for 2018. Pluto will rise in the east at sunset and reach its highest elevation, over the southern horizon, at 1:20 a.m. local time. While Pluto is far too dim to see in amateur-grade telescopes, the planet will be positioned only 12.5 arc-minutes west (to the right) of the magnitude 5.6 star designated 50 Sagitarii. Both objects will fit into the field of view of a telescope at medium-high power (yellow circle). Even if you can’t see it directly, you will know that Pluto is there.
Thursday, July 12 at 10:48 p.m. EDT – New Moon and Partial Solar Eclipse
At its new phase, the moon is travelling between Earth and the sun. Since sunlight is only reaching the far side of the moon, and the moon is in the same region of the sky as the sun, the moon will be completely hidden from view. This new moon will generate a partial solar eclipse that will cross the Antarctic Ocean south of Australia and touch southeastern Australia and Tasmania. Greatest eclipse will occur on the coast of Antarctica at 03:01:07 UT, at which time only 23 percent of the Sun will be obscured. The combined gravitational tugs of the sun and moon will generate large tides on Earth over the following several days.
Saturday, July 14 early evening – Crescent Moon meets Mercury
In the western sky after sunset on Saturday, July 14, look for the young crescent moon sitting about 1.5 degrees (or 1.5 finger widths held at arm’s length) above Mercury. Use the moon to assist you in spotting Mercury with binoculars (orange circle) starting around 9 p.m. local time. The planet will become easier to see as the sky grows darker, until about 10 p.m. local time, just before it sets.
Sunday, July 15 evening – Crescent Moon between Venus and Regulus
In the western sky on the evening of Sunday, July 15, the young waxing crescent moon will take up a position between Venus and Regulus, the brightest star in Leo. The moon will sit 1.5 degrees west (to the right) of Venus and 4.5 degrees east (to the upper left) of the naked-eye star. As soon as you spot the moon in the bright early evening sky, try and find Venus and Regulus on either side of it using binoculars (orange circle), but take care to avoid the sun!
Thursday, July 19 at 3:52 p.m. EDT – First Quarter Moon
After the moon has completed the first quarter of its orbit around Earth, the relative positions of the Earth, sun, and moon cause us to see it half illuminated – on its eastern side. A first quarter moon always rises around noon and sets around midnight, so it is also visible in the afternoon daytime sky. The evenings around first quarter are the best times to see the lunar terrain while it is dramatically lit by low-angled sunlight.
Friday, July 20 evening – Gibbous Moon near Jupiter
Starting in the southern sky after sunset on the evening of Friday, July 20, the waxing gibbous moon will be positioned 3 degrees above bright Jupiter. The two objects will cross the sky together until Jupiter sets around 1 a.m. local time.
Tuesday, July 24 all night – Moon meets Saturn
In the southeastern sky after dusk on the evening of Tuesday, July 24, the full moon will sit 2 degrees to the upper right of bright, yellowish Saturn. The two objects will cross the sky together during the night and will easily fit within the field of binoculars (orange circle) or a telescope at very low magnification. Meanwhile, the moon’s separation from the bright planet will noticeably decrease as the moon slides eastwards in its orbit (green line).
Friday, July 27 at 1 a.m. EDT – Mars at Opposition
Mars reaches opposition at 1 a.m. EDT on Friday, July 27, when the Earth will move between Mars and the sun. That evening, the planet will appear as a very bright, reddish (visual magnitude -2.8) star-like object shining over the southeastern horizon. Even a modest telescope should reveal its 24.2 arc-minute disk (inset). Mars will be well worth observing telescopically during late July but, because it will be sitting 6 degrees below the ecliptic (green line), in the northern USA, it will only achieve a maximum elevation of about 20 degrees above the southern horizon when it crosses the meridian about 1 a.m. local time. Observers farther south will see Mars higher in the sky and through less of Earth’s distorting atmosphere.
Friday, July 27 at 4:20 p.m. EDT – Full Thunder Moon and Total Lunar Eclipse
The July full moon, known as the “Buck Moon,” “Thunder Moon,” or “Hay Moon,” always shines in or near the stars of Sagittarius or Capricornus. This full moon is occurring only 0.6 days after apogee, generating the smallest apparent full moon size of 2018. Meanwhile, a total lunar eclipse will be visible from Africa, the Middle East, India, and western Australia. Eastern Australia and Southeast Asia will see a portion of the eclipse before the moon sets and morning twilight arrives, while for Europe and Eastern South America the eclipse will already be in progress when the moon rises. North America will not see any of this eclipse. Maximum eclipse occurs just east of Madagascar at 20:22 UT. The moon will cross just north of the center of Earth’s umbral shadow, setting up conditions for a very dark eclipsed moon. At greatest eclipse, the moon will be sitting 6 degrees north of Mars.
Saturday, July 28 pre-dawn – Southern Delta Aquariid Meteor Shower Peaks
The Southern Delta Aquariid meteor shower runs annually from July 21 to August 23. It peaks before dawn on Saturday, July 28, but is quite active for a week surrounding that date. This shower commonly generates 15-20 meteors per hour at the peak, but is best seen from the southern tropics, where the shower’s radiant, in Aquarius, is positioned higher in the sky. Unfortunately, the full moon on the peak date will severely limit the shower.
Monday, July 30 pre-dawn – Asteroid Juno Passes a Star
In the eastern sky during the pre-dawn hours of Monday, July 30, the eastward orbital motion (green line) of the large asteroid Juno will carry it close to the naked-eye star Mu (μ) Ceti. Both the distant star and the nearby asteroid will appear together in the field of view of a small telescope at moderate magnification (green circle). Juno will noticeably increase its distance from the star between the time they rise, after 1 a.m. local time, and dawn about 4 hours later.
Tuesday, July 31 all night – Mars at Closest Approach
Although Mars reached opposition a few days ago, its minimum distance from Earth will occur on Thursday, July 31, when it will be 0.385 astronomical units (35.79 million miles or 57.6 million km) from Earth. It won’t be this close again until 2035. During the evenings around opposition and closest approach, even modest telescopes can expect to show Mars’ southern polar cap and large-scale surface patterns, unless dust storms hide the surface. Owners of larger telescopes should try for additional surface details and Mars’ two small moons Phobos and Deimos.
For the early part of July, Mercury will be visible low in the western evening sky between about 9:15 and 9:45 p.m. local time. On the evenings of July 3 and 4, Mercury’s orbital motion will carry it through the southern edge of the Beehive Cluster (also known as Messier 44) in Cancer, but this encounter will be better seen from southern latitudes. The planet will steadily swing away from the sun until it reaches greatest elongation (26 degrees east) on July 12. Around mid-month, Mercury will drop below an already shallow ecliptic and become increasingly harder to see from mid-northern latitudes, ultimately disappearing into the twilight for the last week of July. During July the planet will increase in apparent diameter and decrease in illuminated phase and brightness.
During July, Venus will continue a long and very good apparition in the evening western sky that lasts into early autumn. Each evening through the month, the extremely bright planet will swing wider of the sun while traversing the stars of Leo. In early July, Venus will set at about 9 p.m. local time; an hour later by month end. On the evening of July 9, Venus’ orbital motion will carry it only 1 degree north (to the upper right) of Leo’s brightest star Regulus, and on July 15, the three-day-old crescent moon will land 1.5 degrees west (to the right) of the planet. Venus will continually brighten throughout July, increasing from magnitude -4.1 on July 1 to -4.3 on July 31. At the same time, its apparent disk size will increase by 25 percent and its illuminated phase will decrease from 70 percent to 57 percent.
Mars will spend July moving retrograde (west) through the stars of Capricornus. It will start the month as a bright reddish, late night object visible low in the southeastern sky after 11 p.m. local time and remaining observable until dawn in the southwestern sky. For all of July, Earth’s faster orbital motion will continue to reduce our distance from the Red Planet. As a result, Mars will increase in brightness (from visual magnitude -2.2 to -2.8) and its apparent disk diameter will increase from 21 to 24.3 arc-seconds. Mars will reach opposition on July 27 when it will be 3.2 light-minutes (0.39 au) from Earth and be observable all night long. That same evening, the full moon will pass within 7 degrees north of Mars, and observers in the Eastern Hemisphere will be treated to a total lunar eclipse! Mars’ closest approach occurs on July 31, triggering Mars-themed star parties world-wide since it won’t be this close again until 2035. Mars will be well worth observing telescopically all month but, in the northern USA, it will only climb to a maximum of about 20 degrees above the southern horizon. Observers farther south will see Mars higher in the sky and through less of Earth’s distorting atmosphere.
As July begins, very bright Jupiter (visual magnitude -2.3) will be observable in the western half of the sky between dusk and 2:30 a.m. local time. By month’s end, it will be setting shortly after midnight. The planet will spend the month in central Libra, slowly move westward until July 11, when it will resume eastward prograde motion. This maneuver can be seen by watching Jupiter initially draw away from, and then return towards, the nearby bright double star Zubenelgenubi. From time to time during July, the little round shadows cast by Jupiter’s four Galilean moons will be visible as they cross the planet’s disk. On Sunday, July 8 from 9:37 to 11:46 p.m. EDT, Io’s shadow will transit Jupiter. On the evening of July 20, the waxing gibbous moon will be positioned 3 degrees north of (above) Jupiter.
Saturn will be visible during July as a medium-bright (visual magnitude 0.0), yellowish object low in the southeastern evening sky and moving retrograde (westward) through the stars of northern Sagittarius. Saturn will reach its highest elevation over the southern horizon in late evening. But because the ringed planet reached opposition just days after the June 21 solstice, it will remain very low in the southern sky for observers in the Northern Hemisphere. The rings, which subtend about 42 arc-seconds, continue to be well open while the planet’s northern pole tilts mostly sunward. On the evening of July 24, the full moon will sit 2 degrees to the upper right of Saturn and will easily fit within the field of binoculars (orange circle) or a telescope at very low magnification.
During July, blue-green Uranus (magnitude 5.8) will be moving slowly eastward through the stars of western Aries. In early July, the planet will be observable in the southeastern pre-dawn sky for about 2.5 hours. By the end of the month it will start rising at around midnight, extending the observing time.
Blue-tinted Neptune (magnitude 7.8) will spend July moving retrograde (westward) among the stars of eastern Aquarius – shifting slowly toward that constellation’s naked-eye star Hydor. As an aid in locating the planet, look for it about 4.5 degrees to the east of Hydor and 3 degrees north of fainter Psi (ψ) Aquarii.
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 Tips
Adjust 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.
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.