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, 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 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. You can also capture the night sky by using any of the best cameras for astrophotography, along with a selection of the best lenses for astrophotography.
Read on to 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 and Chris at @Astrogeoguy.
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
January 1: Bright moon near Uranus (evening)(opens in new tab)
On Sunday, January 1, the waxing gibbous moon will rise after mid-day and then linger into the night sky until well beyond midnight. For observers in the Americas, the moon will have just completed an occultation of the magnitude 5.7 planet Uranus. Once the sky darkens in the Eastern Time Zone, look for Uranus shining less than a lunar diameter to the moon's right (or celestial west), allowing the moon and the planet to share the field of view in binoculars and backyard telescopes (green circle).
In more westerly time zones, Uranus will be 3-4 lunar diameters from the moon. Observers in the Canadian Maritimes and eastward across Greenland, Iceland, most of northern Europe, and most of northern and western Russia can observe the occultation starting around 21:00 GMT.
January 2: Mare Imbrium's Golden Handle (all night)(opens in new tab)
On Monday night, January 2, the terminator on the waxing gibbous moon will fall just west of Sinus Iridum, the Bay of Rainbows. That semi-circular feature, 155 miles (249 km) in diameter, is a large impact crater that has been flooded by the same basalts that filled the much larger Mare Imbrium to its east — forming a rounded "handle" on the western edge of the mare.
The "Golden Handle" effect is produced when low-angled sunlight brightens the prominent Montes Jura mountain range surrounding Sinus Iridum on the north and west. Sinus Iridum is almost craterless but hosts a set of northeasterly-oriented wrinkle ridges that are revealed at this phase.
January 3 : Gibbous moon passes Mars (all night)(opens in new tab)
In the eastern sky on Tuesday evening, January 3, the bright, waxing gibbous moon will be shining near prominent, red-tinted Mars.
In the Americas, the Moon will be positioned below (or celestial east of) Mars — close enough for them to share the view in binoculars (green circle). The pair will cross the sky together and set in the northwest before dawn. In the interim, the moon will drift farther from Mars and the diurnal rotation of the sky will lift the moon higher than the red planet.
Around 19:00 GMT observers in most of southern and eastern Africa, Madagascar, and the Maldives can watch the moon occult Mars.
January 4: Quadrantids meteor shower peak (before dawn)(opens in new tab)
Named for a now-defunct constellation called the Mural Quadrant, the annual Quadrantids meteor shower runs from December 26 to January 16. Quadrantids meteors always travel away from a radiant point in the northern sky beyond the tip of the Big Dipper's handle.
This shower commonly produces bright fireballs because it is produced by particles dropped by an asteroid designated 2003EH. The Quadrantids' most intense period, when up to 50 to 100 meteors per hour can appear, lasts only about six hours. The peak will occur on Wednesday, January 4 at 3:00 GMT, which converts to 10 p.m. Eastern Time on Tuesday evening — but the optimal time for viewing Quadrantids in the Americas will be from midnight to dawn on Wednesday, while the showers' radiant will be climbing the northeastern sky. A bright gibbous moon will obscure the fainter meteors before it sets around 4:30 a.m. local time.
January 4: Earth at perihelion (at 16:00 GMT)(opens in new tab)
On Wednesday, January 4 at 16:00 GMT or 11 a.m. EST and 8 a.m. PST, Earth will reach perihelion, its minimum distance from the sun for the year. At that time Earth will be 91.403 million miles (or 147.099 million km) from our star. That's 1.67% closer than our mean distance of 1.0 Astronomical Unit. As winter-chilled Northern Hemisphere dwellers will attest, daily temperatures on Earth are not controlled by our proximity to the sun, but by the number of hours of daylight, we experience.
January 5: Full Moon in the Winter Football (evening)(opens in new tab)
On Thursday night, January 5 the nearly full moon will shine inside the Winter Football, also known as the Winter Hexagon and Winter Circle. The asterism is composed of the brightest stars in the constellations of Canis Major, Orion, Taurus, Auriga, Gemini, and Canis Minor — specifically Sirius, Rigel, Aldebaran, Capella, Castor & Pollux, and Procyon.
After Sirius rises in mid-evening, the huge pattern will straddle nearly 70 degrees of the southeastern sky. Hours later the asterism will stand upright in the south, with the Milky Way passing vertically through it. The hexagon is visible during evenings from mid-November to spring every year. The full moon will shine on its eastern rim on Friday night.
January 6: Dual shadows cross Jupiter (from 00:50 to 02:32 GMT)(opens in new tab)
On Friday evening, January 6, observers with telescopes in southern and eastern Asia and south to western Australia can watch the small, round black shadows of two of Jupiter's Galilean Moons as they slide across that planet's disk at the same time.
At 7:50 p.m. Indochina Time (00:50 GMT), the large shadow of Ganymede will begin to cross Jupiter's southern hemisphere, joining Io's smaller shadow, which began its own passage across Jupiter's equatorial zone at 7:22 p.m. ICT (00:22 GMT). 102 minutes later, at 9:32 p.m. ICT (02:32 GMT), Io's shadow will leave the planet. Ganymede's shadow will complete its own transit at 10:20 p.m. ICT (03:20 GMT). These times will vary by a few minutes depending on your location.
January 6: Full Wolf Moon (at 23:08 GMT)(opens in new tab)
The January full moon, which always shines in or near the stars of Gemini or Cancer, will occur at 6:08 p.m. EST, 3:08 p.m. PST, or 23:08 GMT on Friday, January 6. This one is known as the Wolf Moon, Old Moon, and Moon after Yule. The Indigenous Ojibwe people of the Great Lakes region call it Gichi-manidoo Giizis, the "Great Spirit Moon", a time to honor the silence and recognize one’s place within all of Great Mystery’s creatures. (You might recall that name from hearing or singing Henry Wadsworth Longfellow's The Song of Hiawatha.)
The Cree of North America calls the January full moon Opawahcikanasis, the "Frost Exploding Moon", when trees crackle from the extreme cold temperatures. Full moons during the winter months climb as high in the sky as the summer noonday sun and cast shadows in the same locations. Ray systems radiating from the more recent craters are prominent around the full moon.
January 7: Bright moon joins Gemini's Twins (all night)(opens in new tab)
In the eastern sky on Saturday evening, January 7, the bright, recent moon will shine a palm's width below (or 6.5 degrees to the celestial southeast) of the bright star Pollux in Gemini.
The somewhat fainter star Castor will shine above them. As the trio crosses the sky during the night, the eastward orbital motion of the moon will carry it farther from Pollux. The diurnal rotation of the sky will drop Gemini's stars to the moon’s lower right after midnight local time.
January 8: Asteroid Pallas at opposition (all night)(opens in new tab)
On Sunday, January 8, the main belt asteroid designated (2) Pallas will reach opposition.
On the nights near opposition, Pallas will rise at sunset and set at sunrise, and shine with a visual magnitude of 7.7. That's within reach of binoculars and backyard telescopes, but wait until the asteroid has risen higher in the late evening for the best view of it.
On opposition night, Pallas will be situated in southern Canis Major, several finger-widths to the lower right (or three degrees to the celestial southwest) of the bright star Adhara, and just a finger's width above the medium-bright star Kappa Canis Majoris. On the following nights, the asteroid will slide northwest (red path with labeled dates:time).
January 10: Stellar halo around Mirfak (evening)(opens in new tab)
In mid-evening during January, the constellation of Perseus is positioned nearly overhead in the northern sky. This constellation's location straddling the outer reaches of the Milky Way has filled it with rich star clusters. The largest of these surrounds the bright star Mirfak or Alpha Persei.
Melotte 20, also known as the Alpha Persei Moving Group and the Perseus OB3 Association, is a collection of about 100 young, massive, hot B and A-class stars spanning 3 degrees of the sky. The cluster can be seen with unaided eyes and improves in binoculars (green circle). It is approximately 600 light-years from the sun and is moving as a group. Mirfak is moving with them.
This elderly yellow supergiant star has evolved out of its blue phase and is now fusing helium into carbon and oxygen in its core.
January 12: Mars stands still (all night)(opens in new tab)
On Thursday, January 12, the bright reddish planet Mars will cease its westward motion through the stars of northern Taurus, ending a retrograde loop (red path with labeled dates:time) that began in late October. From this point on, Mars will ramp up its regular easterly prograde motion above the bright reddish star Aldebaran, moving farther away from the nearby Pleiades star cluster (also designated Messier 45) each night.
January 14: Third Quarter Moon (at 02:10 GMT)(opens in new tab)
The moon will reach its third quarter phase on Saturday, January 14 at 9:10 p.m. EST and 6:10 p.m. PST, which converts to 02:10 GMT on Sunday. The moon will rise at about midnight local time, and then remain visible until late on Sunday morning in the southern sky.
At third quarter, 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. The week of moonless evening skies that follow third quarter will be ideal for observing deep sky targets.
January 16: The Pleiades shines high (all night)(opens in new tab)
At about 8 p.m. local time on mid-January evenings, the Pleiades open star cluster, also known as the Seven Sisters and Messier 45 is positioned high in the southern sky.
The rest of its home constellation Taurus, the Bull will be situated below the cluster. Visually, the Pleiades are composed of medium-bright, hot blue stars named Asterope, Merope, Electra, Maia, Taygeta, Celaeno, and Alcyone. In Greek mythology, those characters were the daughters of Atlas, and half sisters of the Hyades. They are indeed related — born of the same primordial gas cloud.
To the naked eye, only six of the sister stars are usually apparent; their parents Atlas and Pleione are huddled together at the east end of the grouping. In binoculars (inset) and backyard telescopes, hundreds of stars appear. Not surprisingly, many cultures, including Aztec, Maori, Sioux, Hindu, and more, have noted this object and developed stories around it. In Japan, it is called Subaru and forms the logo of the eponymous car maker. Due to its shape, the cluster is sometimes confused with the Little Dipper.
January 18: Crescent moon near Antares (pre-dawn)(opens in new tab)
After the waning crescent moon rises in the southeastern pre-dawn sky on Wednesday morning, January 18, it will be accompanied by the bright, reddish star Antares, the heart of Scorpius, twinkling just a thumb's width to its right (or 1.5 degrees to the celestial southwest). The pair will be close enough to share the view in binoculars (green circle) until the brightening sky hides Antares. Watch for Mercury shining off to their lower left.
January 20: Jupiter at perihelion (all day)(opens in new tab)
On Friday, January 20, the giant planet Jupiter will reach perihelion, its minimum distance from the sun for its current orbit.
Today Jupiter will be 460.224 million miles, 740.659 million km, or 4.95 times the mean Earth-sun distance. From here on Earth Jupiter won't look any larger or brighter tonight, but at Jupiter's next six oppositions, the planet will show a diminishing disk size in telescopes. Jupiter will grow in size during the years preceding the next perihelion on December 5, 2034, but it won't be this close to the sun again until the late 2050s.
January 21: New Moon (at 20:53 GMT)(opens in new tab)
The moon will reach its new phase on Saturday, January 21 at 3:53 p.m. EST, 12:53 p.m. PST, or 20:53 GMT.
At that time our natural satellite will be located in southwestern Capricornus, 5.5 degrees south of the sun. This new moon will occur while the moon is at perigee, its closest approach to Earth, producing high tides worldwide.
While new, the moon is traveling between Earth and the sun. Since sunlight can only reach the far side of the moon, and the moon is in the same region of the sky as the sun, the moon becomes unobservable from anywhere on Earth for about a day (except during a solar eclipse). On the evenings following the new moon phase, Earth's planetary partner will return to shine in the western sky after sunset.
January 22: Venus kisses Saturn (after sunset)(opens in new tab)
On the evenings surrounding Sunday, January 22, the brilliant planet Venus will climb past 75 times fainter Saturn in a very close conjunction. The pair will shine above the west-southwestern horizon for an hour after sunset.
The two planets will be binoculars-close (large green circle) from Friday to Tuesday and will share the view in a backyard telescope (small green circle) from Saturday to Monday.
At their closest approach on Sunday, Saturn will be positioned just half a finger’s width to Venus' right (or 20 arc-minutes to the celestial north-northwest), but your telescope may flip them around. Wait until the sun has completely set before using binoculars or telescopes to view them. Observers at southerly latitudes might glimpse the very slim crescent of the young moon nearly a fist's width below the two planets.
January 23: Uranus pumps the brakes (evening)(opens in new tab)
On Monday, January 23, the motion of the distant, blue-green planet Uranus through the background stars of southern Aries will slow to a stop — completing a westward retrograde loop that it began in late August. After today, the planet will begin to creep eastward again.
At magnitude +5.73, Uranus can be seen in binoculars and backyard telescopes, and even with unaided eyes under dark skies. Tonight the planet's small, blue-green dot will be shining a generous fist's width to the lower left (or 12.5 degrees southeast) of Aries' brightest star Hamal - on the line connecting Hamal to Omicron Tauri.
January 23: Crescent moon with Venus and Saturn (after sunset)(opens in new tab)
On Monday, January 23, the slender crescent of the young moon will join the Venus-Saturn conjunction — setting up a wonderful widefield photo opportunity in the west-southwestern sky in the early evening.
The moon, which will be positioned a generous palm's width to the upper left of the two planets, may exhibit Earthshine. Sometimes called the Ashen Glow or the Old Moon in the New Moon's Arms, the phenomenon is visible within a day or two of new moon, when sunlight reflected off Earth and back toward the moon, slightly brightens the unlit portion of the moon's Earth-facing hemisphere.
January 24: Crescent moon passes Neptune and Vesta (evening)(opens in new tab)
On Tuesday evening, January 24, the easterly orbital motion of the waxing crescent moon (green line) will carry it toward Neptune and the large asteroid Vesta. In the Americas, the moon will set while it is still about a palm's width below (or celestial southwest) of them.
Observers across the International Date Line in eastern Asia, New Zealand, and Australia can see the moon posing between them on Wednesday evening when magnitude 7.9 Neptune will be located a generous thumb's width below the moon and magnitude 8 Vesta will shine several finger-widths to the moon's upper left.
January 25: Waxing moon meets Jupiter and Juno (evening)(opens in new tab)
The moon will continue its trip past the planets on Wednesday evening, January 25. Tonight the 23%-illuminated crescent moon will dance several finger widths below (or celestial south-southwest of) very bright Jupiter, close enough for them to share the field of view in binoculars (green circle).
Skywatchers in westerly time zones will see the pair closer together before they drop below the rooftops in mid-evening. The relatively faint, magnitude 9.6 asteroid Juno will be positioned a palm's width to the left of Jupiter all week.
January 26: See the Hyades cluster (all night)(opens in new tab)
Located only about 150 light-years away from the sun, Taurus' triangular face is actually one of the nearest open star clusters to us. It is commonly called The Hyades, named for the five daughters of Atlas in Greek mythology. It also has the designations Melotte 25 and Caldwell 41.
The cluster contains several hundred stars, with a half-dozen or so readily seen under moonless suburban skies, many as close pairs. It's a superb target to view with binoculars (green circle).
The five brightest members, all naked-eye stars, are within a few light years of one another. The cluster's stars likely formed together about 625 million years ago. The bright orange star Aldebaran, at the lower (southeastern) vertex of the Hyades, is actually not part of the cluster. It is less than half as far away! On late January evenings, the Hyades are very high in the southern sky.
January 28: First Quarter Moon (at 15:19 GMT)
When the moon completes the first quarter of its orbit around Earth at 10:19 a.m. EST (or 15:19 GMT) on Saturday, January 28, the relative positions of the Earth, sun, and moon will cause us to see it half-illuminated — on its eastern side.
At first quarter, the moon always rises around mid-day and sets around midnight, so it is visible in both the afternoon daytime sky and during the evening. The evenings surrounding first quarter are the best for seeing the lunar terrain when it is dramatically lit by low-angled sunlight.
January 28: Half-moon buzzes Uranus (late night)(opens in new tab)
On Saturday evening, January 28 in the Americas, the slightly gibbous moon will shine two finger widths to the lower right (or about two degrees to the celestial west) of the magnitude 5.7 planet Uranus.
The moon's eastward orbital motion will carry Luna closely past Uranus during the night, eventually allowing them to share the view in a backyard telescope (green circle). Observers in Alaska, far northern Canada, Svalbard, and Greenland can see the moon occult Uranus starting around 04:30 GMT on January 29. Use an app like Starry Night to determine the start and end times for the occultation where you live.
January 30: Mercury at greatest western elongation (before sunrise)(opens in new tab)
On Monday, January 30, Mercury (orbit shown in red) will reach its widest separation of 25 degrees west of the sun, and maximum visibility for its current morning apparition. With Mercury positioned close to the tilted morning ecliptic (green line) in the southeastern sky, this appearance of the planet will be a relatively good one for both Northern and Southern Hemisphere observers.
The optimal viewing times at mid-northern latitudes will start around 6:15 a.m. local time. Viewed in a telescope (inset) the planet will exhibit a waxing, slightly gibbous phase, and the medium-bright star Omicron Sagittarii will shine nearby.
January 30: Bright moon vs Mars (overnight)
On Monday night, January 30, the waxing gibbous moon will once again shine close enough to the bright reddish dot of Mars for them to share the view in a backyard telescope (green circle).
After dusk in the Americas, look high in the southern sky to see the moon positioned a short distance to Mars' right (or celestial southwest). Through the night, the moon's eastward orbital motion will carry it closely past the red planet while the diurnal rotation of the sky alters the angle between them.
Observers located in the southern USA, Mexico, Central America and northern South America can see the moon occult Mars around 06:00 GMT on January 31. Use an app like Starry Night to determine the start and end times where you live.
Mercury(opens in new tab)
For the first several days of January, Mercury will be visible with increasing difficulty just above the west-southwestern sky as it departs from much brighter Venus and drops sunward.
In a telescope, it will display a waning crescent phase. Mercury will pass the sun at inferior conjunction on January 7 and then it will become observable in the eastern predawn sky after mid-month. On January 18 Mercury will end a westerly retrograde loop. The following morning, the old crescent moon will shine 14.5 degrees to its southwest.
On January 30, Mercury will achieve greatest western elongation, 25 degrees from the sun, and maximum visibility. With Mercury positioned close to the tilted morning ecliptic, the appearance of the planet will be a relatively good one for both Northern and Southern Hemisphere observers.
The optimal viewing times at mid-northern latitudes will start around 6:15 a.m. local time. Viewed in a telescope that day the planet will exhibit a waxing, slightly gibbous phase, with the medium-bright star Omicron Sagittarii shining close by. Only turn your optics towards Mercury if the sun is completely below the horizon.
Venus(opens in new tab)
Venus will remain a feature of the southwestern evening sky during January. Its steadily widening elongation from the sun and the steeper tilt of the ecliptic will lift the brilliant, magnitude -3.8 planet higher into the sky after sunset.
Venus will speed eastward through the stars of Capricornus from January 2 to 23, passing close to some of the Sea-Goat's brighter stars from January 13 to 21. Venus will pass Saturn in an extremely close conjunction on the evenings surrounding January 22, when they'll be separated by only 20 arc minutes. On January 28 it will cross into Aquarius.
Viewed in a telescope during January, Venus will exhibit a nearly fully-illuminated disk that grows from 10.4 to 11.1 arc seconds over the month. The very young crescent moon will shine below (southwest) and to the upper left (east) of Venus-Saturn on January 22 and 23, respectively, making a lovely photo opportunity.
Mars(opens in new tab)
Mars will spend January in central Taurus, positioned about 8 degrees north of its bright reddish star Aldebaran. Only a month after its opposition, Mars will still be an all-night target — although its apparent brightness will halve from magnitude —1.19 to -0.26 over the month. On January 12, Mars' westerly retrograde motion towards the Pleiades cluster will slow to a stop. After that date, Mars will resume its regular eastward prograde motion at an accelerating pace.
Telescope views of Mars during January will display its pale ruddy disk with darker surface features. Its size will shrink dramatically from 14.5 to 10.7 arc seconds and it will wane in the illuminated phase from 97% to 92% — all due to Earth's increasing distance from the planet. The waxing gibbous moon will shine two degrees east of Mars on January 3 and return to sit a similar distance to its west on January 30.
Jupiter(opens in new tab)
Jupiter will be observable during the early evening in January, but by the end of the month, its bright white point of light will be descending the western sky at dusk – shortening the telescope-viewing window then.
The magnitude -2.3 planet will decrease slightly in apparent brightness as it slides steadily eastward through western Pisces. Its distance to the east of much fainter Neptune will increase from 8.5 to 12.6 degrees.
The asteroids Juno and Vesta will chase Jupiter along a parallel track running 6 degrees to Jupiter's south. Juno, the more easterly of the pair, will overtake Jupiter around mid-month.
In a backyard telescope, Jupiter will exhibit dark equatorial bands across a disk that diminishes in size from 39.2 to 36.1 arc seconds. The Great Red Spot will appear every second or third night, and Jupiter's four large Galilean satellites will eclipse and occult one another, and cast round, black shadows on the planet on January 2, 5, 12, and 25. On the evening of January 6, observers with telescopes in southern and eastern Asia and south to western Australia can watch the shadows of Ganymede and Io slide across that planet's disk together for 102 minutes. The waxing crescent moon will shine several degrees to the southwest of Jupiter on January 25.
Saturn(opens in new tab)
Saturn will shine above the southwestern horizon after sunset during January. At the beginning of the month, its yellow-tinted magnitude 0.8 dot will form a small triangle to the right (northwest) of the medium-bright stars Deneb Algedi and Nashira, which form the tail of Capricornus, the Sea-Goat.
Viewed in a telescope during early January, Saturn will show an apparent disk diameter of 15.5 arc seconds. Its rings will subtend more than double that span. Saturn’s motion sunward will reduce its elongation from 42 degrees to 14 degrees over the month, causing the planet to end January shining in twilight just above the horizon near Venus. Venus will pass Saturn in an extremely close conjunction on the evenings surrounding January 22, when they’ll be separated by only 20 arc-minutes, then Saturn will drop lower.
The very young crescent moon will shine below (southwest) and to the upper left (east) of Venus-Saturn on January 22 and 23, respectively, making a lovely photo opportunity.
Uranus(opens in new tab)
The blue-green, magnitude 5.7 planet Uranus will be observable nearly all night long during January.
The planet's 3.7 arc-seconds-wide disk will be most easily resolved in telescopes during the early evening when it will be highest in the sky.
The planet's westerly retrograde motion through southern Aries will slow until it becomes stationary on January 22-23. After that Uranus will slowly begin to move east again.
On the evening of January 1 in the Americas, the waxing gibbous moon will shine just to the east of Uranus. For observers in the Canadian Maritimes and eastward across Greenland, Iceland, most of northern Europe, and most of northern and western Russia, the moon will have occulted Uranus starting around 21:00 GMT. The half-illuminated moon will return to the west of Uranus on January 28.
Observers in Alaska, far northern Canada, Svalbard, and Greenland can see the moon occult Uranus starting around 04:30 GMT on January 29. On nights when the moon isn't nearby, Uranus can be found using binoculars. Look a generous fist’s width to the lower left (or 12.5 degrees southeast of) Aries' brightest star Hamal, and only a palm's width north of the star Mu Ceti.
Neptune(opens in new tab)
During January, the distant, blue planet Neptune will be observable during the early evening as a magnitude 7.9 speck creeping slowly eastward in northeastern Aquarius, near that constellation's border with Pisces.
To aid your search, Neptune will be located between far brighter Jupiter and the medium-bright star Phi Aquarii, which will shine 5.6 degrees to Neptune's west-southwest. Over the month Jupiter's position to the northeast of Neptune will increase from 8.5 to 12.6 degrees. In a telescope, Neptune's tiny apparent disk size will span 2.2 arc-seconds.
Gibbous: Used to describe a planet or moon that is more than 50% 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 fainter objects, such as meteors, dim stars, nebulas, and galaxies, give your eyes at least 15 minutes to adjust to the darkness. Avoid looking at your phone’s bright screen by keeping it tucked away. If you must use it, set the brightness to minimum — or cover it with clingy red film.
Light Pollution: Even from a big city, one can see the moon, a handful of bright stars, and the brightest planets - if they are above the horizon. But to fully enjoy the heavens — especially a meteor shower, the fainter constellations, or to see the amazing swath across the sky that is the disk of our home galaxy, the Milky Way — rural areas are best for night sky viewing. If you’re stuck in a city or suburban area, use a tree or dark building to block ambient light (or moonlight) and help reveal fainter sky objects. If you’re in the suburbs, simply turning off outdoor lights can help.
Prepare for skywatching: If you plan to be outside for more than a few minutes, and it’s not a warm summer evening, dress more warmly than you think is necessary. An hour of winter observing can chill you to the bone. For meteor showers, a blanket or lounge chair will prove to be much more comfortable than standing, or sitting in a chair and craning your neck to see overhead.
Daytime skywatching: On the days surrounding first quarter, the moon is visible in the afternoon daytime sky. At last quarter, the moon rises before sunrise and lingers into the morning daytime sky. When Venus is at a significant angle away from the sun it can often be spotted during the day as a brilliant point of light - but you’ll need to consult an astronomy app to know when and where to look for it. When large sunspots develop on the sun, they can be seen without a telescope – as long as you use proper solar filters, such as eclipse glasses. Permanent eye damage can occur if you look at the sun for any length of time without protective eyewear.