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 email@example.com.
Calendar of Observing Highlights
Tuesday, September 5 overnight - Neptune at opposition near the moon
On Tuesday, Sept. 5, Neptune will be directly opposite the sun in the sky, and visible all night. It is located in Aquarius but is too faint to be seen with the unaided eye. Use binoculars and a star chart from Starry Night. On opposition night the nearly full moon will sit less than 2 degrees to the lower right of the planet. For most of Antarctica and southeastern South America, the moon will pass in front of the planet.
Wednesday, September 6 at 3:03 a.m. EDT - Full Corn Moon
The September full moon, known as the "Corn Moon", always shines in or near the stars of Aquarius and Pisces. Because the moon appears full only when opposite the sun, full moons always rise around sunset and set around sunrise.
Sunday, September 10 pre-dawn - Mercury and Mars near Regulus
On Sunday, Sept 10 low in the pre-dawn Eastern sky, Mercury will sit only 0.6 degrees (less than a finger width) to the right of the bright star Regulus. Dimmer reddish Mars will sit 3 degrees below the pair. For the best chance of seeing them, look between 5:45 and 6 a.m. local time.
Tuesday, September 12 pre-dawn - Mercury reaches greatest western elongation
Due to the steep ecliptic (green line) this month, Mercury delivers an excellent morning apparition for mid-northern latitude observers. On September 12, the planet will reach its widest angle west of the sun and peak visibility. Look low in the eastern pre-dawn sky between 5:30 and 6 a.m. local time. In a telescope Mercury will exhibit a waxing half-illuminated phase.
Tuesday, September 12 pre-dawn – Moon meets Aldebaran
From midnight to dawn on Tuesday, September 12, the waning gibbous moon will pass through the stars marking the triangular face of Taurus the Bull. As dawn approaches, the moon moves towards the bright star Aldebaran. Observers in western North America and Hawaii will see the moon pass in front of the star.
Wednesday, September 13 at 2:25 a.m. EDT - Last Quarter Moon
Last quarter moons rise around midnight and remain visible in the southern sky during morning daylight. At this phase, the moon is illuminated on the eastern side, towards the pre-dawn sun. At last quarter, the moon is positioned ahead of the Earth in our trip around the sun. About 3½ hours later, earth will occupy that same point in space. After last quarter, the moon wanes while traversing the last quarter of its orbit around the earth on the way to new moon.
Saturday, September 16 pre-dawn - Mercury grazes Mars
In the eastern pre-dawn morning sky of Saturday, September 16, Mercury will pass very close to Mars. Observers in western North America and Hawaii will see them especially close together, only a fraction of a degree apart. Regardless of location, the two planets can fit within the eyepiece field of view of a backyard telescope.
Monday, September 18 pre-dawn – Moon visits Regulus, Venus, Mars and Mercury
In the pre-dawn on September 18, the old crescent moon will join a chain of naked eye objects low in the eastern sky. Bright Venus rises first at 4:35 am local time, followed by the bright star Regulus, the moon, dim reddish Mars, and finally Mercury. As its orbit carries it through the objects, the moon will pass in front of Venus for observers in the Indian Ocean region, and then Regulus for those in northern Africa.
Monday, September 18 pre-dawn – Morning Zodiacal Light for Mid-Northern Observers
During moonless periods in September and October annually, the steep morning ecliptic favors the appearance of the zodiacal light in the eastern sky for about half an hour before dawn. This is reflected sunlight from interplanetary particles concentrated in the plane of the solar system. During the two weeks starting just before the new moon on September 20, look south of east, below Venus, for a broad wedge of light rising from the horizon and centered on the ecliptic (marked by green line).
Tuesday, September 19 pre-dawn - Venus kisses Regulus
In the eastern sky from 5 a.m. local time until dawn on Tuesday, September 19, the bright planet Venus will sit about 0.5 degrees to the left of the bright star Regulus. The pair will easily fit in the field of view of binoculars and backyard telescopes.
Monday, September 18-19 pre-dawn – Moon covers Mars and Mercury
In the eastern pre-dawn sky on September 18, observers in northeastern Micronesia and Hawaii will see the moon occult Mars, and those in easternmost Asia, Micronesia, and northern Polynesia will see the moon occult Mercury.
Wednesday, September 20 at 1:30 a.m. EDT - New Moon
At new moon, the moon is travelling between the Earth and sun. Sunlight is only reaching the side of the moon that is turned away from us, and it's in the same region of the sky where the sun is, so it cannot be seen. A day or two after new moon, look for the slender sliver of the waxing crescent moon low above the western horizon.
Friday, September 21-22 early evening - Jupiter and the young Moon
After sunset on Friday, September 21 look low in the western sky for Jupiter sitting about 6 degrees to the left of the young crescent Moon. The pair of objects will set about 8 p.m. local time. The following evening the moon will hop to sit 7 degrees to the upper left of the planet.
Friday, September 22 at 2:02 p.m. EDT – Equinox
On Friday, September 22 at 2:02 p.m. EDT, the sun crosses the celestial equator moving southward, causing the days to grow shorter in the northern hemisphere and longer in the southern hemisphere.
Tuesday, September 26 evening - Moon meets Saturn
In the southwestern evening sky on Tuesday, September 26, yellowish Saturn will sit 3 degrees to the lower left of the waxing crescent Moon, making a nice sight in binoculars.
Wednesday, September 27 at 10:54 p.m. EDT - First Quarter Moon
At first quarter, the positions of the Earth, sun, and moon cause us to see one-half of the moon illuminated by the sun - on the western (right-hand) side. A first quarter moon rises around noontime and sets around midnight, so it is visible starting in the afternoon hours. The term quarter moon refers not to its shape, but the fact that our natural satellite has now completely the first quarter of its orbital journey around Earth since the last new moon.
Mercury spends September in its best morning apparition of the year for mid-northern latitude observers. Peak visibility occurs around its greatest angle west of the sun on September 12, when it is best observed from 5:30 to 6:30 am local time. The planet lands near Regulus on September 10 and very close to Mars on September 16. Observers in easternmost Asia, Micronesia, and northern Polynesia will see the moon occult Mercury before dawn on September 19.
Extremely bright Venus continues to descend sunwards in September, shining in the eastern pre-dawn sky. It begins the month among the stars of Cancer (it is one degree from the Beehive Cluster on the 1st) and ends in Leo, passing only 0.5 degree from the bright star Regulus on the 20th. On September 18, the moon will occult Venus for observers in the Indian Ocean region.
Mars re-appears in the eastern pre-dawn sky during September, and spends the month climbing away from the sun through the stars of Leo. On the 5thand 6thit passes about one degree to the left of the bright star Regulus, with Mercury positioned 2 degrees to the right. On September 16th, Mercury passes close enough to Mars for the pair to fit in the field of view of a backyard telescope. On September 19, observers in northeastern Micronesia and Hawaii will see the moon occult Mars.
During early September, bright Jupiter shines low in the southwestern evening sky, moving prograde through Virgo, a few degrees above the bright star Spica. By month end, it will be difficult to see within the evening twilight glow, setting about 9 pm local time. On Friday evening September 22, the young crescent moon will sit approximately 7 degrees to the upper left of the planet.
Yellow-tinted Saturn spends September in the southwestern sky beside the Milky Way in southern Ophiuchus, and visible with naked eyes starting at dusk. It sets about 12:30 am local time on the 1stand just after 10:30 pm at month end. This year Saturn sits low in the southern sky, making telescope views less than ideal from mid-northern latitudes. As a consolation prize, the ring plane is tilted at near its maximum extent toward the Sun and Earth. On Tuesday, September 26, Saturn will sit 3 degrees to the lower left of the waxing crescent Moon, a nice sight in binoculars.
During September, blue-green Uranus rises in mid evening and remains well placed for viewing until pre-dawn. It is moving slowly retrograde about one degree above the modest star Torcularis (Omicron Piscium) in southern Pisces. At visual magnitude 5.7, it is observable in binoculars and with the naked eye under dark skies.
Dim blue Neptune reaches opposition on September 5, making it observable all night in telescopes, albeit somewhat low in the southern sky. During the month it moves retrograde (westwards) in Aquarius about one degree below the minor star Hydor.
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.