Skylights: March 2025

March 2025  :  Jim Hendrickson

The March 2025 sky offers us several notable events to look forward to: a total lunar eclipse on the 13th-14th, a partial solar eclipse at sunrise on the 29th, and the inner planets Mercury and Venus put on their best performances of the year as both dive towards inferior conjunction.

March gives us our last good look at the winter constellations as its most prominent asterism, the Winter Hexagon, is conspicuously west of the meridian after dusk by month’s end. The stars comprising the hexagon, clockwise from north, are Capella in Auriga, Aldebaran in Taurus, joined by Jupiter, Rigel in Orion, Sirius in Canis Major, Procyon in Canis Minor, and Pollux and Castor in Gemini, joined by Mars at this time.

The stars of autumn can still be found in the northwest early in the evening, including Andromeda with its signature grand spiral galaxy, and Cassiopeia, which rotates about the circumpolar sky to its lower culmination just after midnight.

In the east, the spring constellations are coming into view, as Ursa Major, Leo, and Hydra assume their rising prominence. By mid-month, Arcturus, in Bootes, will be above the northeastern horizon after dusk, and the Northern Crown, Corona Borealis, with its Blaze Star still expected to undergo its outburst, is visible by the mid-evening hours.

The ideal time to conduct the annual Messier Marathon, when a single night’s observing can net all 110 of the famous deep-sky objects, occurs between March 16-20th for our latitude, however, bright moonlight will probably defer any effort until after the 23rd, when some of the early pickings are already lost to twilight.

Sun

The annual march forward to Daylight Saving Time occurs at 2:00am EST on the 9th. From then until November 2, we will be 4 hours behind Coordinated Universal Time (UTC-4). This pushes sunset well into the 6:00pm hour, and sunrise goes back, for another five days, past 7:00am.

The Sun crosses from Aquarius into Pisces on the 12th, and will spend the next 37 days within the constellation of the fishes.

Equinox occurs at 5:01am on the 20th. Although the term means “equal night,” due to the Sun appearing as a distinct disk rather than a point source, combined with atmospheric refraction of objects near the horizon, the true date of equal night occurs three days earlier, on the 17th.

The first 7:00pm sunset is on the 22nd. The Sun does not set earlier than 7:00pm again until September 12.

The most notable event in March is a partial solar eclipse that is in progress for us at sunrise on the 29th. It begins at 5:24am, when the Sun is still below the horizon. Maximum eclipse is at 6:13am, which is also before our 6:33am sunrise.

The Sun will be located at 85° azimuth when the solar disk is fully above the horizon, and the obscuration extent will be 41%, with the silhouette of the Moon positioned evenly horizontally over the left portion of the solar disk. This orientation remains relatively preserved as the pair rises higher into the sky, and the Moon uncovers more of the Sun, although just before the Moon exits, it will appear slightly below horizontal orientation with respect to the Sun.

The entire eclipse is over at 7:06am, when the Sun is 5.7° above the horizon.

Moon

Moon-Venus pairings are always a stunning sight in a twilight sky. Although this month’s will not be as close as February’s 2° separation, it will still be worth watching the 5.2% illuminated crescent, with its Earthshine-lit globe, 6.3° south of the brilliant planet on the 1st.

The Moon will be receiving a new visitor from Earth on the 2nd, as the Firefly Aerospace Blue Ghost Mission 1 lander is scheduled to land within Mare Crisium, carrying 10 instruments that are part of NASA’s Commercial Lunar Payload Services program.

On that evening, gaze upon the 12.0% illuminated crescent Moon hanging over the western horizon with a telescope or binoculars. The most prominent feature on the sunlit portion of the Moon is the nearly circular, 550-kilometer-wide basin known as Mare Crisium, the "Sea of Crises." During the early days of the lunar cycle, Mare Crisium occupies nearly the entire breadth of the illuminated crescent, and its smooth floor appears in stark contrast to deep shadows of its rim, as the feature is undergoing lunar sunrise during this phase.

Blue Ghost Mission 1 won’t be the first craft to touch down in Mare Crisium. In August 1976, the Soviet Luna 24 sample return probe landed there, and subsequently returned 170 grams of lunar regolith, the third successful robotic sample return from the Moon.

On the 4th, the Moon is 4.0° north of Uranus.

The waxing crescent Moon is 5.5° west-southwest of the Pleiades cluster on the 5th. While this is not a spectacularly close pairing, it should be a worthwhile sight in binoculars, especially later in the evening, closer to Moonset.

The Moon is first quarter, in Taurus, at 11:32am on the 6th. Just past midnight that evening, it passes 0.4° south-southeast of Elnath (beta Tauri). 

Early in the evening of the 7th, the Moon is 4.2° north-northeast of the open cluster M35 in Gemini.

Early the following evening, the 8th, the gibbous Moon is 1.1° north-northeast of Mars.

At 5:00am on the 12th, the nearly full Moon is just 0.9° north of Regulus, in Leo.

A total lunar eclipse coincides with the full Worm Moon early in the morning of the 14th. The penumbral eclipse begins at 11:57pm on the 13th, and the Moon enters the umbra at 1:09am.

Total eclipse begins at 2:25am, and extends for 66 minutes, with mid-eclipse occurring at 2:59am. The umbral phase ends at 4:47am, and the penumbral phase ends at 6:00am.

The Moon is 3.5° west of Antares on the 20th.

Early in the morning of the 28th, a challenging pairing of the 1.5% waning crescent Moon and Saturn is visible less than 20 minutes before sunrise, with the Moon just 0.4° north of Saturn.

New Moon, which gives us a partial solar eclipse, occurs on the 29th, beginning Lunation 1264.

Following the eclipse, an opportunity to sight a very young, 13-hour, 0.5% illuminated waxing crescent Moon exists for 34 minutes after sunset.

The following evening, the 30th, presents a far easier chance to observe the beautiful  3.5% crescent Moon and its Earthshine, setting just after 9:00pm.

Mercury

The most favorable evening apparition of Mercury of the year takes place during March.

On the 2nd, Mercury is 2.0° north of Neptune.

Mercury exhibits a gibbous phase until the 7th, when it is 50% illuminated, and shows a narrowing crescent thereafter.

Latest Mercuryset for this apparition occurs at 8:19pm on the 9th, 94 minutes after sunset.

Mercury tracks with Venus in the western sky for several days mid-month, with the two planets at their closest, at 5.5°, on the 12th.

From the 18th, Mercury sets within an hour of sunset, and on the 21st, just 30 minutes.

Mercury’s evening apparition ends on the 24th, when it passes inferior conjunction.

Following conjunction, you can follow it into the morning sky by looking about 5.5° below (southeast of) Venus. Both planets will display remarkably thin crescents, but Mercury remains low, dim, and difficult to observe before sunrise.

Venus

Venus, a brilliant beacon in our evening sky for most of the past seven months, quickly dives out of view as its faster orbit brings it between us and the Sun, an event known as inferior conjunction, on the 22nd. But before it gets there, it puts on quite a show for observers with even the smallest telescopes as its large, thin crescent changes appearance each evening.

Also, because Venus lies north of the ecliptic by about 8.5°, combined with the high angle of the ecliptic on the western horizon during this time of year, it is possible to observe Venus right up to inferior conjunction. If you do manage to observe it on the evening of conjunction, when it will be just 0.281 au from Earth, its crescent is just 1.0% illuminated, and nearly one arcminute across.

It is notable that Venus passes through the non-zodiacal constellation Pegasus from the 22nd through the 23rd.

Also, due to its position north of the ecliptic, it will be technically possible to observe Venus both in the evening and morning from the 13th through the 23rd, but only on the 19th and 20th will it be visible at least 30 minutes before sunrise and 30 minutes after sunset.

Later in the month, Venus becomes easier to observe in the morning. On the 25th, it is 8.8° directly above the Sun, and its 1.2% illuminated, 59 arcsecond wide crescent will be oriented with its cusps oriented exactly parallel to the horizon.

Beginning on the 30th, Venus will be visible at least an hour before sunrise.

Mars

As Mars passed its stationary point late last month, it has resumed its prograde (eastward) motion through Gemini. 

The waxing gibbous Moon is 1.1° north-northeast of Mars on the 8th.

From the 9th onward, Mars’ disk is less than 10 arcseconds.

The Red Planet is dimming slightly as Earth moves away from it, but remains 0th magnitude throughout the month.

We are 1 au from Mars on the 16th.

Jupiter

Jupiter reaches its point of eastern quadrature (90° elongation) on the 1st, and a few hours later, on the 2nd, it is at minimum illuminated fraction, when observing the planet  through a telescope reveals a 99.05% gibbous phase. While this miniscule difference may be difficult to see visually on Jupiter’s oblate disk, telescopic observers may notice how the planet’s western limb is just a bit softer or less well-defined than its eastern limb under higher magnification on nights of exceptional seeing. The distinction is more pronounced when Jupiter is imaged with a planetary camera.

The Moon appears near Jupiter through the evening of the 5th-6th. The pairing will be especially interesting to watch as the nearly first-quarter Moon and Jupiter set together in the west-northwest at 1:00am, when they will be 5.6° apart.

Jupiter’s moons

The moons are in tight formation on the 4th, with Ganymede’s shadow and Europa transiting Jupiter from twilight. Europa begins to emerge from transit at 6:34pm. Ganymede’s shadow transit ends at 8:08pm, followed by Europa’s at 9:11pm. To the west of Jupiter are Europa, Ganymede, and Callisto. Io begins to emerge from eclipse at 9:27pm.

On the 10th, the moons are arranged in order of their orbital radius to the east of Jupiter.

A double transit of Europa and Ganymede can be seen at 7:42pm on the 11th. Their respective shadows cross the planet a short time later.

On the 13th, a close pairing of Europa and Io (north to south) occurs, and the two point towards Callisto, farther to the south, at 8:33pm.

Another close pairing of Europa and Io is on the 16th at 7:51pm.

On the 18th, for a brief time between 10:52pm and 11:52pm, Jupiter appears to have one single moon (Callisto). This occurs when a double transit of Europa and Ganymede is in progress, and Io is in occultation.

Early on the 20th, Jupiter appears to have just two moons, Callisto and Ganymede, until Io emerges from eclipse at 8:48pm. Europa emerges 80 minutes later.

An askew line of Ganymede, Callisto, and Io appears to the east of Jupter at 10:02pm on the 22nd. Within two hours, Io moves out of line to form a compact triangle with the other two moons.

Two pairs, one on the east (Callisto and Ganymede, and one to the west (Europa and Io) form a “double-double” arrangement on the 23rd.

On the 24th, there is another arrangement of the moons in order of orbital radius, extending to the east of Jupiter.

After midnight on the 26th, and just before Jupiter sets, there is a very tight arrangement of Io to the west, and Europa and Ganymede to the east of the planet. Callisto is visible farther out to the east.

From 7:42pm to 10:43pm on the 27th, Jupiter appears to have just two moons, as Io and Europa pass behind the planet.

On the 30th, Callisto assumes an unusual position just beyond Jupiter’s south pole at 9:45pm.

Saturn

The ringed planet gives us much to talk about, but not much to see during the month of March. Saturn, like Earth and all other planets, has an axial tilt, and goes through seasons. Unlike the other planets of our solar system, Saturn’s axial tilt can be easily observed, its tell-tale indicator being its broad ring system.

Saturn’s rotational axis is tilted 26.7° from its orbital plane, and it orbits the Sun once every 29.45 years, making each season on Saturn roughly 7.36 years long, and the interval between equinoxes 14.72 years. Saturn is approaching one of those equinoxes in early May.

When Saturn reaches equinox, not only is each of its hemispheres equally exposed to the Sun, but its ring plane also reaches an angle of incidence of 0°, so sunlight falls on neither side of the rings, and the rings cast an exceedingly miniscule shadow on the planet. During this time, the rings aren’t completely dark, despite the lack of sunlight, because they are significantly illuminated by “Saturnshine,” light reflected from the globe of Saturn itself, just as a crescent Moon is back-illuminated from light reflected from Earth, known as Earthshine.

Although Saturn’s equinox is still a few weeks away, the offset angle between Earth and the Sun as seen from Saturn, a product of Saturn’s orbital inclination with respect to the ecliptic, 2.49°, as well as Earth’s position along its orbit,  results in Earth intercepting the ring plane at a different date than on Saturn’s equinox, and that date arrives on March 23.

During our ring plane crossing, Saturn’s rings are still tilted 0.8° relative to the Sun, and would, if Saturn were to be better-placed in our sky, cast a thin but visible shadow just south of the planet's equator.

However, because Saturn is at conjunction on the 12th, it will be too close to the Sun (less than 10°) when Earth crosses the ring plane on the 23rd, so the event will pass mostly unnoticeable to us.

On May 6, when Saturn reaches equinox, Earth will be offset 2.7° with respect to the ring plane, so we will see the “underside” of the rings, which will be illuminated by Saturnshine.

Although we will miss the March 23 ring-plane crossing since Saturn is more or less behind the Sun from our view, we can look forward to November 24, when we move to the opposite side of our orbit, and get to see the rings at minimum angle of just over 0.5° while the planet is still well-placed for observing high in our sky.

On the 28th, the 1.5% waning crescent Moon is just 0.4° north of Saturn.

Uranus

As Uranus has maintained a high perch in the evening sky during the past few months, March presents the last good opportunities to observe it before it sinks into springtime’s rapidly encroaching evening twilight.

The seventh planet enters Taurus, where it will spend the next seven years, on the 3rd. It can be easily located 7.5° southwest of the Pleiades cluster, and shines at magnitude 5.8.

On the 4th, the 32% waxing crescent Moon is 4.0° north of Uranus.

By month’s end, Uranus is within 7° west-southwest of the Pleiades, placing it just within the same binocular field of view.

Neptune

Neptune reaches conjunction on the 19th and will not be visible in our March sky. The distant planet will be visible in the morning sky later next month.

Minor Planets

Vesta, at magnitude 7.0, is 2.8° northwest of Zubeneschamali (beta Librae) early in the month. Brightening to 6th magnitude, it reaches its stationary point on the 21st, 2.4° north-northwest of Zubeneschamali, then moves retrograde towards the northwest.

Ceres is in Aquarius, behind the Sun and out of view.

Pluto is in western Capricornus, and rises just before the start of astronomical twilight, but remains low in the southeastern sky and is difficult to observe.

The distant dwarf planet Makemake reaches opposition in Coma Berenices, on the 31st. At a distance of 51.80 au, its dim 17.0 magnitude glow should be bright enough to be detected with most astronomical imaging cameras.