December 2025 offers a packed skywatching calendar for observers in the Toronto area. From a final supermoon of the year to the Geminid meteor shower and a rare interstellar comet, there’s plenty to see. The Winter Solstice brings the longest nights, giving stargazers ample time to enjoy bright planets, sparkling winter constellations, and multiple meteor showers. Below is a comprehensive guide (with times in local EST) to all the notable celestial events this month – including where and when to look for each. Let’s explore what’s happening in the sky this December 2025!
The Moon in December 2025
The calendar of lunar phases for December 2025. (Scott Sutherland/NASA SVS)
Moon Phases and “Cold Moon” Supermoon
Dec 4 – Full Cold Moon (Supermoon): December’s full moon, traditionally called the Cold Moon (also known as the Oak Moon or Long Nights Moon), occurs on Thursday, Dec 4 at 6:14 pm EST. This is an extreme supermoon, arriving just ~12 hours after lunar perigee, which means it appears about 8% larger and 16% brighter than an average full moon. Like all full moons in winter, this moon soars high in the sky around midnight and shines all night long (rising at sunset and setting at sunrise)space.com. Fun fact: The Ojibwe of the Great Lakes call this moon “Little Spirit Moon” (Manidoo Giizisoons), a time of purification and healing.
Dec 11 – Last Quarter Moon: On Thursday, Dec 11 at 3:52 pm EST, the moon reaches its third (last) quarter phase. That evening, observers will see a half-illuminated moon (lit on its western side). The last quarter moon rises around midnight local time and is visible in the morning sky, setting around midday. The week after this phase provides dark evening skies ideal for deep-sky stargazing, since the moon won’t be up in the early night hours.
Dec 19 – New Moon (Micro Moon): The moon is new on Friday, Dec 19 at 8:43 pm EST. At New Moon the lunar disk is invisible, as it lies between Earth and Sun. This New Moon occurs just ~3 days after the Moon’s farthest point in its orbit (apogee), making it a micro new moon. With the moon absent from the night sky, the dark nights around Dec 19–21 will be perfect for observing faint stars, nebulas, and the Ursid meteors.
Dec 27 – First Quarter Moon: The moon’s first quarter phase comes on Saturday, Dec 27 at 2:10 pm EST. That evening you’ll see a half-moon (lit on its eastern side) high in the south at dusk among the stars of Pisces. First quarter moons set around midnight, so they remain visible through the evening. The days around first quarter are great for lunar observing – the slanting sunlight along the lunar terminator (the day-night line on the Moon) dramatically highlights the Moon’s craters and mountains. Also on Dec 26-27: For telescope users, the famous “Lunar X” and “Lunar V” optical illusions become visible on the Moon’s terminator on Dec 26 around 8:00–9:30 pm EST, just before first quarter. These appear as a striking X and V shape of illuminated peaks along the shadow line, a few hours before the half-moon is exactly reached.
Lunar Conjunctions & Occultations
Dec 5 – Moon Occults the Bull’s Horn (Elnath): On the night of Dec 5, the nearly full Moon will be positioned in the constellation Taurus, not far from the star Elnath (Beta Tauri). In Toronto the Moon will shine between the horns of Taurus (below Capella and above Orion) all night. In certain parts of the world, this alignment results in an occultation of Elnath – observers across northwestern Australia, Indonesia, and Papua New Guinea on Dec 5–6 can watch the Moon cover and then uncover this 1.6-magnitude star. (No such occultation occurs in North America, but it’s interesting to know it’s happening elsewhere!) If you were in those locales, you’d need to check local timing – for example, in Port Moresby the star disappears at 11:35 pm local time Dec 5 and reappears about 73 minutes later.
Dec 6 – Moon Joins Jupiter in Gemini: On Saturday Dec 6, look toward the east in the early evening to find the bright waning gibbous Moon shining in central Gemini – and just above dazzling Jupiter. The Moon and Jupiter travel together across the sky all night, moving westward and drawing closer to Gemini’s twin stars Castor and Pollux by dawn. In the pre-dawn hours of Dec 7, the Moon will form a broad arc underpinned by Procyon (in Canis Minor) to the west and Capella high to the north – with Jupiter and the Gemini twin stars nestled in between. This grouping makes a great sight and photo-op, with the Moon and Jupiter being the two brightest objects in that part of the sky.
Dec 8 – Moon Buzzes the Beehive: Before dawn on Monday Dec 8, the waning gibbous Moon will drift near the Beehive Cluster (Praesepe, M44) in the constellation Cancer. Around 6:00–6:30 am EST, look southwest (relatively high in the sky before sunrise) to spot the Moon with the Beehive’s faint sprinkling of stars about 3° to its northwest. The cluster’s stars spread over an area about twice the size of the full Moon. They are just barely visible to the naked eye in a dark sky, but the Moon’s presence will make them tough to see without aid. Use binoculars to fit the Moon and the Beehive in the same field of view – you’ll notice dozens of tiny stars “swarming” near the Moon. (Observers further west in, say, western North America, will see the Moon even closer to the cluster before dawn.)
Dec 9 – Moon & Regulus (Occultation for Northern Canada): Late on Tuesday Dec 9, the waning gibbous Moon rises in the east with Regulus, the bright alpha star of Leo, shining just below it. The pair will climb higher through the night and be visible in close proximity until dawn. Thanks to the Moon’s orbital motion, an occultation of Regulus will occur for observers in far-northern locations: parts of northern/eastern Canada, Greenland, Iceland, and Scandinavia will see the Moon briefly cover Regulus in the overnight hours. (For example, around 11:00 pm MST in Edmonton the Moon’s bright edge covers Regulus, with the star reappearing about 30 minutes laterspace.com.) In Toronto, the Moon will pass just a few arcminutes north of Regulus but will not eclipse it – however, you’ll still get to enjoy the close pairing. Feel free to watch with the naked eye or through binoculars; lunar occultations of stars are perfectly safe to observe.
Dec 18 – Ultra-Thin Moon, Mercury & Antares at Dawn: Thursday Dec 18 presents a challenging but lovely dawn sight. About 40–30 minutes before sunrise (roughly 7:00–7:30 am EST in Toronto), a very thin waning Moon (only ~5% illuminated, as New Moon is just a day away) will be barely above the southeast horizon. If you have a clear view toward the SE, you might catch this old Moon sitting a few degrees to the upper left of Mercury and a few degrees to the upper right of Antares, the red-orange heart of Scorpius. Antares will be low in the twilight (and may be visible to the naked eye if the sky is still dark enough), with Mercury shining a bit higher and brighter. The Moon itself will be just to Mercury’s lower right – an extremely slim crescent. Binoculars can greatly help pick out the Moon against the dawn glow. This trio will be easier to see from more southerly latitudes (where they’ll be a bit higher), but determined observers in Toronto might snag a last look at the Moon before it vanishes into the glare. (Be very careful to stop looking once the Sun is about to rise!)
Dec 26 – Moon Meets Saturn & Neptune: On Dec 26 (the day after Christmas), the waxing half-moon will make a lovely grouping with two outer planets. As darkness falls (around 6–7 pm local), find the first quarter Moon about halfway up the southern sky. Nearby, just a few degrees to the Moon’s lower left, will be the distinct golden point of Saturn. Fainter Neptune (magnitude ~7.8, invisible to unaided eyes) will also be positioned a few degrees from the Moon, slightly below Saturn – all three objects can fit within a binocular field. Enjoy watching Saturn’s steady yellow-white glow next to the Moon. As the evening progresses, this trio moves lower toward the southwest and sets around midnight. If you have a telescope, this night is also a chance to observe the Lunar X (as noted above, visible around 8–9:30 pm EST on the Moon’s terminator. By the way, also nearby in the sky is dwarf planet Ceres (magnitude ~7), residing a few degrees southeast of Saturn – but you’ll need optical aid and a star chart to pick out Ceres among the background stars.
Dec 31 – Moon Skirts the Pleiades (Again): Fittingly, the Moon closes out the year with another meeting with the Pleiades. On New Year’s Eve, Dec 31, the nearly full waxing gibbous Moon will once again pass by the Pleiades cluster during the evening hours. For observers in far eastern Asia (e.g. Japan), this encounter on Dec 31 actually results in a lunar occultation of the Pleiades for a couple of hours around 11 pm JST. In Toronto, when night falls on Dec 31, we will see the Moon just to the west of the Pleiades – specifically, the Moon will be shining above Aldebaran (the eye of Taurus) and about a fist’s width to the right (west) of the Pleiades cluster. Although not as dramatic as the earlier Pleiades pass on Dec 3, it’s still a nice sight – a bright nearly-full Moon amidst the winter stars to ring in the New Year.
Visible Planets (December 2025)
December’s long nights are filled with planet spotting opportunities, especially for Jupiter and Saturn. Here’s what to expect from the naked-eye planets this month in Toronto:
Mercury: The elusive innermost planet puts on its best morning show of 2025 for Northern Hemisphere observers. Mercury is visible low in the SE sky before sunrise during the first three weeks of December. It reaches greatest western elongation (21° from the Sun) on Dec 7, when it shines around magnitude –0.5 and appears about 6–7° above the southeast horizon about 30–45 minutes before sunrise. Thanks to the steep angle of the ecliptic in winter, this apparition is quite favorable for Toronto. Try spotting Mercury around 6:30 am in early December – it looks like a modest “star” twinkling against the dawn. It will remain visible (brightening slightly) until around Christmas, after which it sinks back into the Sun’s glare. Tip: Around Dec 17–18, Mercury will be very close to the super-thin waning Moon and the red star Antares in early dawn (see above), though all three will be challenging to see in bright twilight.
Jupiter: Jupiter rules the night! The gas giant is at its biggest and brightest of the year, heading for opposition in early January. In early December, Jupiter (mag ~–2.5) rises by mid-evening (around 8–9 pm) in the east, and by late December it’s rising by dusk and visible all night. Jupiter spends the month in the constellation Gemini. It actually brightens a bit further to about –2.7 magnitude by the end of December. Look for Jupiter high in the south around 2–3 am in early month (culminating around 3 am), and by midnight at year’s end. Through binoculars, you can easily spot Jupiter’s four Galilean moons near the planet on any given night. A telescope will reveal the planet’s cloud belts, and occasionally the Great Red Spot or moon shadows crossing Jupiter’s disk. Notably, Jupiter sits among the bright winter stars – by late month it forms an “extra star” in the Winter Hexagon asterism, near Gemini’s bright twins and not far from Orion. Don’t miss: On Dec 6–7, the Moon will be near Jupiter (see above), and on Dec 14 the Geminid meteors will radiate not far from Jupiter’s vicinity in the sky.
Saturn: The ringed planet is a evening highlight in December. Saturn (around magnitude +0.9 fading to +1.0) is found in Aquarius, and it’s already up in the south by nightfall. In Toronto, Saturn appears as a moderately bright, steady yellow-white “star” in the south-southwest at dusk, reaching its highest point in the south earlier in the evening and then moving toward the west. It sets by around midnight local time in mid-December. Saturn resumed direct (eastward) motion in late November and will slowly advance through Aquarius’s stars this month. Even a small telescope will show Saturn’s rings, which are nearly edge-on this year (only about 1° open) – a unique sight, as the rings appear as a thin line. Several of Saturn’s moons (like Titan) are also observable with a telescope on clear nights. Saturn will be visited by the Moon on Dec 26 (see above), making for an excellent conjunction that evening.
Uranus: Uranus is well placed for observation this month, located in southern Taurus not far from the Pleiades. Fresh off its late-November opposition, Uranus (mag ~5.6) can be observed most of the night in December. It rises in the east during early evening and is highest around 10 pm, then moves to the west in the early morning hours. From a dark site, some keen-eyed observers can barely spot Uranus without optical aid (it’s right on the naked-eye visibility threshold). However, for most in the Toronto area with light pollution, you’ll need binoculars or a small telescope to see it. In binoculars, Uranus will appear as a tiny star-like point with a subtle blue-green tint. On Dec 3, the bright moon passes a few degrees above Uranus, and on Dec 30–31 the Moon again will be in Taurus not far from Uranus. Otherwise, no dramatic events for Uranus – but it’s a good time to check this ice giant off your observing list while it’s still conveniently placed.
Neptune: Distant Neptune is visible with optical aid in the evenings. Neptune (mag ~7.9) resides in western Pisces, hovering not far from Saturn in the sky (about 4° to Saturn’s NE). It’s already high in the south at dusk and will be observable until around 11 pm – 12 am before it gets low. You will need a telescope or strong binoculars to spot Neptune (it will look like a dim, bluish “star”). On Dec 11, Neptune ends its retrograde motion and resumes moving eastward against the stars. The Moon’s close approach on Dec 26 will make Neptune harder to see that evening due to moonlight, but on nights when the Moon is absent, try to find Neptune by first locating Saturn and then scanning a few degrees away (a star chart or app can help pinpoint it). Neptune sets by around midnight in mid-December.
Meteor Showers and Comets
December brings multiple meteor showers – most notably the Geminids, one of the year’s best – as well as a couple of faint comets (including an interstellar visitor). Here’s what to watch for:
Bright meteors streak through the sky during a meteor shower. The Geminids are known for producing many slow, colorful fireballs.
Dec 13–14 – Geminid Meteor Shower: The Geminids are December’s main event for meteor enthusiasts. Active each year from late Nov to Dec 24, the Geminids peak on the night of Dec 13–14. This year’s conditions are nearly ideal – the moon will be only a waning crescent (about 25% lit) and rises late, so it won’t wash out the show much. Under dark skies, the Geminids can produce up to ~120 meteors per hour at peak (in theory), and 50+ per hour is common even a day before or after peak. In 2025 the peak is expected in the wee hours of Sunday, Dec 14 (around 2 am local time) for North America. Geminid meteors radiate from the constellation Gemini (near the bright stars Castor and Pollux, not far from Jupiter’s position this year), which means the shower is visible all night in the Northern Hemisphere – the radiant rises in mid-evening, so you can start looking by 9–10 pm on Dec 13 and see meteors through dawn. Geminid meteors are often bright, slow, and vividly colored (occasionally leaving lingering trails). To observe them, find the darkest sky you can and look upward (not just at Gemini – meteors can appear anywhere in the sky, though their trails will point back to the radiant). After midnight is best, once Gemini is high overhead. Dress warmly, get a lounge chair, and give your eyes 20+ minutes to adapt to the dark. With luck, you’ll catch dozens of shooting stars – including some spectacular fireballs streaking across the winter sky.
Dec 21–22 – Ursid Meteor Shower: The Ursids are a smaller meteor shower that peak just before Christmas. They are active around Dec 17–26 each year and will peak in the predawn hours of Monday, Dec 22 (late night Dec 21 into early Dec 22). The Ursids emanate from the Ursa Minor constellation – the radiant is near Kochab in the Little Dipper, not far from the North Star, meaning it’s high in the northern sky all night for Toronto. This year’s Ursid peak comes just two days after the new moon, so dark skies will provide good conditions. However, the Ursids are a minor shower, usually offering ~5–10 meteors per hour at best. Occasionally the Ursids have surprise outbursts, but typically they’re a low-key event. If you’re up late on the longest nights of the year, you might catch a few modest meteors scooting away from the Little Dipper. Try watching after midnight on Dec 21/22 for slightly higher rates as the radiant climbs higher. Dress warmly and temper expectations – any Ursid “shooting star” you catch will be a bonus treat for the holiday season.
Dec 19 – Interstellar Comet 3I/ATLAS (closest approach): A visitor from beyond our solar system is in our skies this month! Comet 3I/ATLAS – the third known interstellar object – makes its closest approach to Earth on Dec 19, 2025. On that date it will still be a vast 170 million miles away (approximately 1.8 AU, nearly twice the Earth–Sun distance), so it’s not dangerous – but astronomers are excited to study it. For backyard astronomers, Comet 3I/ATLAS unfortunately won’t be bright enough to see with the naked eye. It is estimated around magnitude 13 at peak brightness, which means you’ll need at least an 80–150 mm telescope and dark skies to spot it. If you have the equipment, look for it in the early morning hours, in the constellation Leo. By around 4–6 am in mid-December, Leo will be rising in the east. The comet will appear as a faint smudge in long-exposure images or through a scope. Because 3I/ATLAS is an interstellar comet, it’s essentially passing through the Solar System only this once – after the end of the year it will dim as it recedes and eventually head back into interstellar space. Even though we can’t easily see it, having an interstellar visitor is a notable event making December 2025 extra special.
Winter Solstice and Notable Stars
Dec 21 – Winter Solstice: Sunday, Dec 21 marks the Winter Solstice in the Northern Hemisphere. At 10:03 am EST on Dec 21, the Earth’s North Pole is tilted at its farthest from the Sun, and we experience the shortest day and longest night of the year. In Toronto, the sun will follow its lowest, shortest arc across the sky on the 21st. (Conversely, the Southern Hemisphere will be having its Summer Solstice with the year’s longest day.) Astronomically, the December solstice is the start of winter in the north. After this date, the daylight hours will slowly begin to lengthen. Culturally, many traditions observe this turning point of the seasons – from ancient Yule celebrations to modern holiday festivals. For skywatchers, the solstice means extended darkness for stargazing. Around the solstice you can enjoy the winter stars for nearly 15 hours from dusk to dawn. The Sun’s extreme southern position also means the noon Sun is very low in the sky (only ~23.5° above the horizon in Toronto on Dec 21). If you’re curious, you might even try observing (safely, with appropriate solar filters!) the midday Sun’s low angle, or note the long noontime shadows cast on this day. After Dec 21, the sun will start its slow climb northward again – a reminder that winter’s deep freeze will eventually give way to spring.
Dec 25 – Sirius, the “Christmas Star”: On Christmas night, step outside and look toward the southeastern sky to find a sparkling celestial jewel – Sirius, the brightest star in Earth’s night sky. Sirius (magnitude –1.4) rises above the horizon in Toronto by around 7:30 pm EST on Dec 25. It’s located in the constellation Canis Major (the Big Dog), earning it the nickname the “Dog Star.” Many refer to Sirius as a “Christmas Star” simply because of its prominence on winter nights. Once Sirius clears the rooftops and trees, it’s unmistakable – a brilliant bluish-white star twinkling fiercely. In fact, because Sirius doesn’t climb very high from our latitude (it stays in the lower southern sky), its light must pass through a lot of atmosphere, causing it to flicker in vivid colors like a shimmering holiday light. Around midnight on Dec 25–26, Sirius reaches its highest point due south – but “high” is only about 22° above the horizon from Toronto. If you have a very steady hand or a telescope, you might attempt to spot Sirius’s companion, the tiny white dwarf known as Sirius B, which is lurking just 10″ away from the dazzling primary star (a challenge even in larger telescopes). For most, though, simply admiring Sirius’s intense brightness is rewarding – remember, it’s only 8.6 light-years away, making it one of our nearest stellar neighbors. Together with Orion’s Belt and other bright stars, Sirius helps form the beautiful Winter Hexagon pattern dominating the December night sky. So as you enjoy the holidays, take a moment to look up at Sirius sparkling on Christmas night – it’s like nature’s own festive beacon twinkling down on us.
Enjoy your December stargazing! With its long nights and a rich lineup of events, December 2025 has something for everyone – whether you’re following the Moon through its phases and close encounters, catching planets at dusk and dawn, watching meteors paint the sky, or simply marveling at the winter stars on a cold night. Bundle up, clear your schedule for those peak dates, and look up – the night sky over Toronto is putting on a fantastic show this month. Clear skies and happy holidays!