Rare comet-moon conjunction tonight

Tonight (Friday, Jan. 23rd) the moon will pass only about 1°  (two moon diameters) south of Comet 15P/Finlay as seen from the Americas. This map shows the view from the upper Midwest at 7 p.m. Two 6th magnitude stars in Pisces are labelled. Created with Chris Marriott’s SkyMap software

I want to alert you to a rather unusual event occurring this evening.

If you read yesterday’s blog, you know about the triple shadow transit of Jupiter’s moons Io, Europa and Callisto. That’s scheduled for late tonight.

Earlier, around nightfall, the crescent moon will lie 1° or less to the south-southwest of comet 15P/Finlay. No doubt lunar glare will hamper the view some, but what a fun opportunity to use the moon to find a comet.

The farther south you live, the closer the moon will approach the comet tonight. This diagram shows the view from Tucson, Ariz. at nightfall when less than 1/2° will separate the two. At about the same time (~7 p.m. local time) the moon will occult or cover up a 6th magnitude star (seen poking out from its left side). Source: SkyMap

Finlay underwent a flare in brightness last week when it became easily visible in binoculars.

Though a crescent moon isn’t what you’d call a glare bomb, I can’t predict for certain whether you’ll still see the comet in binoculars tonight or need a small telescope instead. Most likely a scope. Finlay has faded some since its outburst and now glows around magnitude +8.5.

You can try with a 10×50 or larger glass, and if you don’t succeed, whip out your telescope; a 4.5-inch or larger instrument should handle the job. Just point it at the moon at star-hop a little to the north-northeast using the map until you see a fuzzy spot with a brighter center. That’s your comet. The tail won’t be visible unless you’re using more firepower, something closer to 10-inches.

Comet Finlay in outburst on January 20, 2015 showing a beautiful parabolic-shaped head. Credit: Joseph Brimacombe

By the way, the father south you live, the closer the moon approaches Finlay. From the far southern U.S. they’ll be just 1/2° apart. Keep going south and parts of Central and South America will actually see the earth-lit edge of moon approach and then occult the comet from view!

* UPDATE: Although light clouds marred the view I had difficulty finding the comet this evening in my 10-inch scope. It’s possible it’s further faded or my conditions weren’t optimal or both. No luck BTW in binoculars.

Snake-tongued Comet Lovejoy slithers north, slowly fades

Right now Comet Lovejoy’s faint, double-rayed gas tail extends many degrees to the east of the bright coma. Observers using 10×50 and similar binoculars have traced it out to 10° or more. This photo was taken on Jan. 18th. Credit: Chris Schur

Forked tongues allow snakes to smell in stereo – each fork senses slightly different chemicals in the snake’s vicinity and feeds a separate signal to its brain. When combined, they create a complete “picture” of the reptile’s odiferous world. In much the same way, the two ears on opposite sides of our heard allow us to hear the world in rich stereo sound.

Comet Lovejoy’s nucleus is jetting gas and dust just like Comet 67P/Churyumov-Gerasimenko in this photo taken by the Rosetta spacecraft on November 22, 2014 from a distance of 18.6 miles (30 km). The nucleus is deliberately overexposed in order to reveal the faint jets of activity. Credits: A/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Lovejoy’s forked tail is hardly an operative organ, but it’s sure amazing sight for stereo eyes. Composed principally of carbon monoxide gas, each of the two primary rays is incredibly well-defined. Gases like water vapor, carbon monoxide and carbon dioxide boil off the nucleus as the Sun warms the comet and help create its big blue-green head or coma. As described here before, the solar wind ionizes or electrifies the gases which allows the magnetic fields embedded in the wind to peel back the gases to form a the glowing gas or ion tail.

Comet Lovejoy arcs up into Triangulum the Triangle later this week and continues into Andromeda into Cassiopeia. Northern hemisphere observers are favored, while those in the southern hemisphere will soon see the comet drop below their horizon. This chart shows Lovejoy’s position every 5 days around 7 p.m. (CST). Stars to magnitude +6. Click to enlarge. Created with Chris Marriott’s SkyMap software

I hope you’ve had the chance to see Comet Lovejoy. While the naked eye view isn’t impressive (though always a pleasure to behold any comet without optical aid), binoculars clearly show the faint, smoky tail extending east of the fuzzy head. In a telescope, even a fairly large one like the 15-inch (37-cm) reflector I use, the fainter rays are indistinct, though the forked tongue shows a little more clearly.

With the moon now returning to the evening sky (see below) and the comet starting to fade, it will gradually become more difficult to see with the naked eye. By mid-February, Lovejoy will probably have dimmed to the naked eye limit of around magnitude +6. But if you use binoculars, you’ll be able to follow our feathery friend through full moon and beyond.

The returning thin crescent moon gathers with brilliant Venus and fading Mercury low in the west-southwest sky during twilight this evening January 21st. This map shows the sky about 40-50 minutes after sunset. Stellarium

Northern skywatchers are fortunate that the comet continues to move north and ever higher in the sky. By late February it will be circumpolar from many locations and remain visible all night.

You can use the map to help you find Lovejoy as it climbs into Triangulum the Triangle this weekend and from there to Andromeda and Cassiopeia.

Can you feel the Love(joy) tonight? Winter comet now at its best

Comet Q2 Lovejoy sports a faint, blue tail about 5 long while near the Pleiades star cluster last night. The head or coma of the comet is easily visible with the naked eye; the tail shows up in binoculars as a thick, smoky streak pointing to the northeast. The glowing patches in the cluster are caused by cosmic dust reflecting starlight. Details: 200mm telephoto at f/2.8, ISO 800. Credit: Bob King

Darkness came in heaps and lingered for hours last night. Although Comet Q2 Lovejoy competes well with the glare of the city and isn’t hard to see from my driveway, I craved something closer to a classic 18th century, electricity-free sky. That meant putting another 25 miles between me and Duluth.

This photo map will help you find the comet in the next few nights as it passes the Pleiades star cluster. Dates are shown at right from Jan. 11-19. Look high in the southeast at nightfall to spy the dipper-shaped cluster then look about one fist to its right. The comet looks like a dim, slightly fuzzy star of 4th magnitude. Credit: Bob King

From the countryside it was easy to just find the Pleiades or Seven Sisters star cluster and jump from there to the comet. As you can see from the photo map, Lovejoy will be near the cluster the next few nights. There’s still no moon in the sky, so I encourage to go out now for a look if you haven’t already. Even if you’ve seen it once or two, the comet bears watching every clear night. Fluctuations in the solar wind continuously change the shape, length and appearance of the ion or gas tail that’s so outrageously beautiful right now.

Comet Lovejoy time exposure made through an 8-inch (20-cm) telescope on January 14th. Beautiful! Click to immerse yourself. Credit: Gerald Rhemann

To my eyes, Lovejoy looked a little brighter (magnitude +3.8) last night than a week ago when it was closest to Earth. Even in 50mm binoculars you can see the pale blue color of the head or coma. The spectacular tail rays depicted in deep photos are much harder to make out. I could just detect a couple of them faintly in a 15-inch telescope when I moved the bright coma out of the field of view and allowed my eyes to fully dark-adapt. Tapping the telescope to bounce the comet around helped to make them stand out better.

Insane high resolution view of Comet Lovejoy’s ion or gas tail on January 11th. Heat from the Sun is responsible for cooking comet ice, which vaporizes and releases gases and dust to form a tail. UV light from the Sun then ionizes or electrified the gases and the solar wind wraps around the comet and drags them into multiple tail rays. Credit: Damian Peach

We’ve got about another week of dark, moonless skies ideal for comet watching. Perihelion or closest approach to the Sun occurs on January 30th, so Lovejoy’s brightness may remain constant during this time even as it moves farther from Earth.

Did you catch the Saturn-moon conjunction this morning? It was cloudy in Duluth, Minn. but around 7:15 a.m. a few brief holes opened up, showing the pair. Credit: Bob King

While you’re at it, point your binoculars at the nearby Pleiades for a face-full of stars. They’re my favorite in binocular cluster because the group comes alive with far more stars than are visible with the naked eye.

I hope you were able to see the conjunction of Saturn and crescent moon earlier today. I wasn’t able to see it at the optimal time in a dark sky at the start of dawn, but we still got a glimpse here.

On Sunday I’ll include a brand new map for tracking Comet Lovejoy over the next two weeks as it continues its northward climb.

Waning moon moons Saturn at dawn tomorrow

Saturn lies just a degree from Beta Scorpii, a fine double star for small telescopes. Tomorrow morning a waning lunar crescent will join the pair in a fairly close conjunction. This photo shows the sky facing southeast at the start of morning twilight. Credit: Bob King

Have you seen Saturn at dawn yet? No? Here’s a great excuse to go out. The waning crescent moon squeaks just 1° north of the planet tomorrow morning in a close conjunction. It all happens not far from Antares, the fiery heart of the summertime constellation Scorpius the Scorpion.

Look low in the southeast tomorrow morning (Friday) Jan. 16th just when the sky starts to brighten at dawn. First you’ll notice the moon. Right below it will be Saturn, and one degree below Saturn, the sweet double star Beta Scorpii. Source: Stellarium

I know that getting up at 6 or 6:30′s not much fun, but I’m convinced that if you act boldly and wisely (dress well for the cold), you’ll return to the warmth of your home a half-hour later with a smile on your face.

Seeing the conjunction requires no optical aid whatsoever, though a pair of binoculars will show nice details on the moon as well the smoky glow of earthshine on the portion not illuminated by the Sun. Saturn requires only a telescope magnifying 30x or higher for a good view.

Saturn, its fab rings and brightness moons depicted for Friday morning. Source: Stellarium

While we’ve been sleeping, Saturn’s rings have been tilting ever more in our direction. Now at mid-month, they’re tipped nearly 25° – almost to their 27° max – and really look showy.

Saturn never travels alone, preferring instead to sally about with its grand family of moons. The diagram above shows the positions of the brightest ones tomorrow morning around 6:30 a.m. (CST).

Saturn in late August 2014. We currently view the north face of the rings. Credit: Paul Maxson

Finally, you’ll notice a modestly bright star just south of Saturn. That’s Beta Scorpii or Graffias, one of the sky’s best and brightest double stars. The 2.6 and 4.5 magnitude stars nestle together like chicks in a nest. Even a 3-inch telescope will show them.

So get out there and say “hi!” to the ringed planet tomorrow.

Moon perambulates with Uranus tonight

The half-moon creeps up on the planet Uranus this evening. The two will be near each other all night in the constellation Pisces, but closest – less than one-third of a moon diameter apart – just before midnight (CST). The views are what you’ll see in a pair of binoculars. The 4th magnitude star Delta Piscium is at top in the field. Source: Stellarium

Sunlight. Moonlight. Starlight. I saw all three for the first time in weeks yesterday. Filled with photons, I feel lighter today, less burdened. Ready to float off the floor.

Seattle, two time zones west of the Midwest, will see the two closest around 9:30 p.m. local time. Source: Stellarium

There’s a nice event you’ll want to see tonight if only because it’s so effortless. The half-moon will pass very close to the planet Uranus for skywatchers across North America this Sunday evening Dec. 28th.

Pop the rubber lens caps off those binoculars and point them at the moon. If you look a short distance to the left you’ll notice a star-like object. That’s the planet!

You can do this anytime it’s dark, but the later you look the better because the moon moves eastward and closer to the planet as the hours tick by. Early in the evening, the two will be separated by a couple degrees, but around 11:30 p.m. CST (9:30 p.m. PST) when the moon reclines in the western sky, the planet will dangle like an solitary diamond less than a third of a lunar diameter away. When closest to the Moon, Uranus may prove tricky to see in its glare. If you hide the Moon behind a chimney, roofline or power pole, you’ll find it easier to see the planet.

Binocular view from the desert city of Tucson around 10:45 p.m. local time tonight. The moon’s farther north of the planet compared to the view from Seattle because the 1,500 miles between the two cities is enough to shift the moon’s position against the background stars. Source: Stellarium

The farther north you live, the closer the twain will be. Skywatchers in Japan, the northeastern portion of Russia, northern Canada and Alaska will see the moon completely hide Uranus for a time.

The farther west you are, the higher the moon will be when they conjoin. West Coast states see the pair highest when they’re closest.

The radically different character of each world can best be appreciated in a telescope. Pump the magnification up to 150x and slide both planet and moon into the same field of view. Uranus, a pale blue dot, wears a permanent cover of methane-laced clouds where temperatures hover around -350°F (-212°C).

Though the moon will be lower in the sky at closest approach, observers in the eastern U.S. and Canada will still see planet and moon just 1/2 degree apart before moonset. Source: Stellarium

The fantastically large-appearing moon in contrast has precious little atmosphere and its sunny terrain bakes at 250°F (121°C). And just look at those craters! First-quarter phase is one of the best times for moon viewing because the terminator or shadow-line that divides lunar day from night slices right across the middle of the lunar landscape.

Shadows cast by mountain peaks and crater rims are longest and most dramatic around this time because we look squarely down upon them. At crescent and gibbous phases, the terminator is off to one side and craters and their shadows appear scrunched and foreshortened.

The day-night line or terminator cuts across a magnificent landscape rich with craters and mountain ranges emerging from the lunar night. Several prominent lunar “seas” or maria and prominent craters are shown. Credit: Christian Legrand and Patrick Chevalley / Virtual Moon Atlas

Enjoy the view and consider the depth of space your view encompasses. Uranus is 1.85 billion miles from Earth today — 7,700 times farther away than the half moon.

Stargazing on Christmas night

Merry Christmas and a happy holiday! I hope you’re enjoying time with family and friends and a clear night is in the forecast. Should you poke your head out tonight, here’s what’s up.

Look for the crescent moon and Mars in the southwestern sky at the end of twilight tonight December 25th. Comet Finlay and Mars will still be tight the next few nights.  The alignment is line-of-sight only — the two are actually about 45 million miles apart. Stellarium

At nightfall, a pretty crescent moon ornaments the dim constellation of Capricornus not far from Mars. Barely half a degree to the planet’s east a 6-inch or larger telescope will net you Comet 15P/Finlay, now fading from its recent outburst. It’s currently magnitude 9.6 with a little tail pointing to the east.

Comet 15P/Finlay passed only 1/6th of a degree from Mars on December 23-24. This photo was taken on the 24th and shows the glaring planet and comet almost touching. Click for a map to help you find Finlay in your telescope. Credit: Damian Peach

In a remarkable coincidence, comets have passed very close to the planet Mars twice this year. Comet Siding Spring drew physically close on and around October 19th, while Comet Finlay only appears next to the planet thanks to a lucky line-of-sight alignment.

A grand entry of stars dances across the southeastern sky around 10 o’clock local time. Comet C/2014 Q2 Lovejoy will be 10° high at that hour in the constellation Columba the Dove as seen from the northern U.S. and even higher from the central and southern states. Stellarium

Later tonight, around 10 o’clock, look to the south. Orion has now climbed boldly into view along with sparkling Sirius and the “Winter Triangle” figure. Tucked below Lepus the Hare you’ll find our Christmas comet, Lovejoy, now glowing at magnitude 5.5 and faintly visible to the naked eye from a dark sky location. Binoculars show it as a big ball of fuzz. For more information and a map showing its travels in the coming nights, click HERE.

Comet Lovejoy on December 23 looks like a Roman candle with a blue coma and long, faint tail. Credit: Michael Jaeger

Photos of Lovejoy show a huge coma or comet atmosphere more than half the size of the full moon tinted green from fluorescing carbon and cyanogen molecules; its super-skinny tail glows blue from light given off by carbon monoxide excited by ultraviolet light from the Sun.

Jupiter is easy to see now in the eastern sky in Leo around 10 o’clock local time. Stellarium

If you now direct your gaze to the east around 10 p.m., Jupiter jumps right out. After Sirius and the moon, it’s the brightest nighttime object the sky this winter. Use the planet to help you find the Sickle or head of Leo the Lion and its brightest star, Regulus.

Jupiter in binoculars tonight around 10 p.m. (CST). All four of its bright moons will be strung out in a nearly straight line very close to the planet (big glow at center). Stellarium

Sharply-focused and steadily held 10x binoculars will show all four of its bright moons, assuming one or more aren’t passing either behind or front of the planet or in eclipse. Lucky for us, Io, Europa and Ganymede will line up in a neat row east of Jupiter with Callisto well off to its west tonight. How many will you see?

Wow! What a blast. This fireball lit up Japanese skies early this morning. The Belt of Orion is at upper right. Credit: SonotaCo

Finally, reports are coming in about a powerfully bright fireball that streaked across Japan’s skies around 2 a.m. local time this Christmas morning. I’ve not been able to track down a brightness estimate, but the pictures show an object at least as brilliant as the full moon.

Venus returns, joins exceptionally young moon tonight

Look low in the southwestern sky starting about 20 minutes after sunset this evening for a little spark of light – Venus. About 5° (one binocular field of view) to its upper right you might glimpse the moon, just 20 hours old from the East Coast (21 hours from the Midwest, 22 hours from the mountain states and 23 hours from the West Coast.) Source: Stellarium

Have you noticed something missing lately? Venus has been absent from view since late last summer. We last saw it struggling against the solar glare at dawn.

Now, just in time for the holidays, Venus is returning to the evening sky, low in the southwest after sundown. Tonight there’s even a chance to see it next to an exceptionally thin crescent moon.

Look for the goddess of beauty and love to meet up with the moon some 20 minutes after sundown low in the southwestern sky. Most of us consider seeing a day-old crescent moon quite a feat, but from the Midwest this evening, Luna will be just 21 hours old, a fragile crust if ever there was and a chance to break your personal young moon record.

I’d bring binoculars just to be sure you see the two. Venus will be only 6° above the horizon this evening. Make slow horizontal sweeps with your binoculars to the left of the brightest part of the lingering glow of sunset. As long as the sky is haze-free, Venus should pop into view. Once you’ve nailed it, move to the upper right in the field of view and locate the moon. Now, lower the binoculars and try sighting both with your naked eye alone.

Venus revolves around the Sun interior to Earth’s orbit. Right now it’s still near its greatest distance from Earth on the opposite side of the Sun from us. Over the coming weeks and month, it will draw closer to Earth and grow in apparent size as its phase changes from full to crescent. Source: Wikipedia with additions by the author

Venus underwent superior conjunction on October 25th, when it lined up with the Sun on the opposite side of its orbit from Earth. It was most distant from us then and appeared like a tiny full moon. The planet’s still pretty far away and will remain near the Sun in evening twilight for the next month or so. Although Venus’ orbital speed varies little over its nearly circular orbit, it appears to travel very slowly this winter because it’s very far from us.

Fear not! Its appearance this month is a harbinger for this spring and early summer’s exceptional apparition when the brightest of the planets will catch your eye in the west all evening long.

Looking at the diagram, notice that Venus, moving faster than Earth because it’s closer to the Sun, is slowly catching up with our planet. As it does, the angle it makes to Sun and Earth continuously changes which changes the appearance of Venus. Through a small telescope we can easily see its phase shrink from full to half to crescent exactly like the phases of the moon.

Panels illustrating several of the closest and best conjunctions of Venus and the planets in the coming year. Source: Stellarium

Venus is famous creating spectacular scenes with other bright planets and the moon. We call these events conjunctions. I’ve illustrated a few of them above. The best will occur on July 1st when the sky’s two brightest planets will be just 0.4° apart.

I love it when Venus returns to view. It always puts a bright face on every clear night.

Moon and Jupiter with a side of JUICE, please

The waning gibbous moon lingers near Jupiter tonight and tomorrow night (Dec. 11) in the constellation Leo. This map shows the sky facing east around 11 p.m. local time. Source: Stellarium

Find the moon tonight and you’ll be led straight to Jupiter. Tomorrow night, too. Earth’s only satellite will spend the next two evenings wooing the largest planet which shines brightly to the west of Leo’s Sickle.

As Jupiter rises earlier and earlier, pushing higher into the evening sky, the European Space Agency’s JUpiter ICy moons Explorer Mission or JUICE recently got the green light to proceed to the next stage of development – working out the details of payload equipment and mission support among the many partners involved in the project.

JUICE will launch in 2022 and arrive at Jupiter in 2030 to begin a three-year-plus study of the giant planet and three of its largest moons – Ganymede, Callisto and Europa. The spacecraft will bristle with cameras, spectrometers, a radar, an altimeter, radio science experiments and sensors used to monitor the flow of charged particles (electrons, protons and others) in the Jovian system.

Artist impression of JUICE at Jupiter in the year 2030. JUICE will spend part of its mission in orbit around Ganymede, the moon at upper left. Credit: ESA/AOES

Scientists will explore Jupiter’s atmosphere, tenuous dust ring and its magnetosphere, a bubble of magnetism that enshrouds the planet similar to the one that funnels the solar wind into Earth’s upper atmosphere to spark auroras. No surpries – Jupiter has auroras, too.

JUICE will also investigate each of the three moons up close and their interactions with Jupiter, especially Ganymede. Detailed investigations Ganymede, the planet’s largest moon, will be performed when the probe enters into orbit around it – the first time any moon other than our own has been orbited by a spacecraft.

Europa, Ganymede and Callisto are all believed to hold oceans of liquid water beneath their frigid crusts. The mission will study the moons as potential habitats for life as it seeks to determine what conditions are required for planet and moon formation and the emergence of life.

This artist’s concept of Jupiter’s moon Ganymede, the largest moon in the solar system, illustrates the “club sandwich” model of its interior oceans. Credit: NASA/JPL-Caltech

JUICE will first visit Callisto, the most cratered object in the solar system, then fly by Europa twice, making measurements of the thickness of its icy crust. In 2032 the spacecraft will enter into orbit around Ganymede and study both its surface and internal structure including that possible hidden ocean.

“JUICE will give us better insight into how gas giants and their orbiting worlds form, and their potential for hosting life,” said Prof. Alvaro Gimenez Canete, ESA’s Director of Science and Robotic Exploration.

What? Two Full Moons this weekend?

A bright waxing gibbous moon dons a colorful corona as passing altocumulus clouds diffract its light earlier this week. Click photo to find the time of moonrise where you live. Credit: Bob King

Lovers of moonlight, this is your weekend. The moon’s essentially full two nights in a row. Full phase doesn’t occur until 6:27 a.m. (CST) tomorrow morning or midway between the two nights. That means tonight’s moon appears in the east about 12 hours before full, while an equally filled-out moon will shine just 12 hours after full Saturday night.

Only a sharp-eyed observer would notice a half-day’s difference in the moon’s phase, so for most of us, the moon will look full both nights. What’s more, it happens to be in one of the coolest places in the sky, smack in the middle of the Hyades star cluster not far from Taurus’ brightest star Aldebaran.

Tonight’s moon will appear in the middle of the V-shaped Hyades star cluster. At a distance of 153 light years, it’s the closest star cluster to the solar system. Stellarium

The moon’s brilliance will make the star cluster difficult to see with the naked eye, but binoculars will offer up a fabulous view of our satellite ensconced in Hyades like an ornament amid twinkling holiday lights.

You can also watch the moon glide eastward and approach Aldebaran during the hours before midnight. At 11 p.m. (CST), they’ll be just 1.4° apart.

Aldebaran is more than twice as close to Earth as the Hyades; it hovers in the foreground and is unrelated to the cluster. Looking up tonight, our gaze will plumb all three dimensions of the sky in a single glance – from the relatively closeness of the moon to the middle distance of Aldebaran and further to the more distant Hyades.

Happy nights adrift on the Moon’s Sea of Showers

Over 700 miles across, Mare Imbrium (Sea of Rains) is the largest lunar sea. Its roughly circular shape is defined by a series of mountains ranges just coming into good view tonight and the next few nights. Credit: Joseph Brimacombe

If you’re looking for a great little place to point a small telescope the next few nights, let me suggest Mare Imbrium, the largest of the lunar “seas”. That’s Latin for Sea of Showers or Sea or Rains. Lovely name. The last time it rained there was never.

Wide view of the whole Moon with the Imbrium basin circled. While Imbrium is the largest lava-filled “sea”, the largest basin, the South Pole-Aitkin Basin, is 1,600 miles in diameter. Credit: Silvercat/Wikipedia

All the Moon’s seas are enormous basins excavated by asteroid impacts between 3.1 and 4.2 billion years ago. Cracks and fissures in the Moon’s crust from the collisions served as conduits for deeper lava to rise and fill the basins with molten rock. These great pools cooled and solidified, forming the large grey spots that make up the face of the Man in the Moon that even a child notices today.

Ruptures in the Moon’s crust caused by the impact of large meteorites/asteroids creates what astronomers call multi-ringed basins. They look like bulleyes, a fitting comparison under the circumstances. Credit: Steven Dutch

Many of the seas are ringed by mountain ranges formed by faulting of the lunar crust during the impacts aided by slumping of material off the fresh slopes.

Earth’s mountains in contrast are lifted up when tectonic plates collide or pile up during volcanic eruptions.

Three ranges shape the outer boundary of the Sea of Rains – the Carpathians, the majestic Apennines and Caucasus. The Alps form part of a second inner ring of peaks. Each is named for its sibling range in Europe. Over the next few nights we’ll see all four cast awesome shadows as the Sun rises over their craggy peaks.

This is how our featured region of the Moon will appear tonight from the Americas. Mountain ranges are labeled in black, craters in white. Credit: Virtual Moon Atlas / Patrick Chevalley and Christian Legrande

Tonight features the Alps, Apennines and Caucasus and the spectacular craters Plato and Copernicus. Tomorrow night, the Carpathians, north of Copernicus, come into view. The reason these features look most dramatic now rather than closer to full Moon is because the terminator cuts across the region. Along the terminator, the boundary separating lunar day from night, the Sun is just rising and every little peak casts a shadow.

The Apennines Mountains is host to the Moon’s tallest mountain, Mt. Huygens, with an elevation of 18,046 feet (5.5 km). Credit: M. Galfalk, G. Olofsson, and H.-G. Floren; SIRCA camera Nordic Optical Telescope with annotation by the author

While binoculars will reveal Plato, Copernicus and the mountain rings, a small telescope will show the scene best. I wish you a clear and not-too-cold night!