Skylights: July 2025

Sun

Earth reaches the most distant point in its orbit around the Sun, known as aphelion, on July 3. At about 4:00pm, we will be at a distance of 1.016644 au (152.1 million km, 8.5 light minutes) from the Sun. This is 0.03332 au (4.99 million km, 12.71 lunar distances, 16.6 light seconds) more distant than we were at perihelion, which occurred on January 3.

While it may not be apparent yet that the amount of daylight is getting shorter, the last day of the year with 15 hours of daylight is July 10.

The Sun moves from Gemini to Cancer on the 20th, and is located 1.0° south of the Beehive Cluster, M44, on the 29th.

Moon

The Moon reaches its first quarter phase at 3:30am on the 2nd, in Virgo. On the evening of the 3rd, the 8-day gibbous is 2.3° south-southeast of Spica, that constellation’s brightest star.

Watching the Moon occult, or pass in front of, a bright star is one of the most dramatic yet simple to observe phenomena, easily visible with small telescopes or binoculars.

The Moon moves nearly imperceptibly slow in our sky, and stars are so distant that they have no discernible size, that when they pass behind the limb of the Moon they appear to wink out and reappear instantaneously. Witnessing these events through the eyepiece of a telescope is quite memorable, and the opportunity to see one occurs just after midnight on the 6th-7th, when the 86% illuminated gibbous Moon occults Fang (pi Scorpii), a magnitude 2.9 class B star that is 337 light years distant. The occultation begins when the darkened limb of the Moon passes in front of the star at 1:01am. The star reemerges from the northeastern limb of the Moon at 2:00am, just a few minutes before moonset.

On the evening of the 7th, the Moon is 4.1° east-southeast of Antares, the class M supergiant marking the heart of Scorpius.

The Moon is full at 4:37pm on the 10th, and rises in the southwest at 8:47pm.

While June’s Strawberry Moon was the most southerly of the year, July’s Full Buck Moon is nearly as low, culminating at just 21.7° over the southern horizon at 1:12am on the 11th. The Moon reaches its most southerly declination on the 10th, which can be observed when the Moon transits at 19.5° above the southern horizon at 12:18am.

The Moon is last quarter, in Pisces, at 8:38pm on the 17th.

On the morning of the 16th, bring out binoculars or a telescope with very low magnification to see the 68.9% waning gibbous Moon, Neptune, and Saturn all within a 3° field of view. The best alignment occurs at about 3:00am-4:00am.

On the 20th, the waning crescent Moon can be seen very close to the Pleiades. It will, in fact, begin to occult the brightest stars of the cluster, but that doesn’t begin until 4:38am, when the sunlit limb of the Moon passes over magnitude 3.7 Electra. This is, unfortunately for us, well into nautical twilight, making the occultation quite difficult to observe.  However, admiring the view of the 24% illuminated crescent, with Earthshine, positioned just west of the cluster in the hours before twilight will be quite easy.

Don’t miss the 2.6% illuminated, 27-day-old Moon near Jupiter on the morning of the 23rd. The pair is separated by 4.6°, and rises just before 4:00am, about 100 minutes before sunrise.

The Moon is new at 3:11pm on the 24th, marking the beginning of Lunation 1266.

On the 25th, the 2-day crescent Moon is 1.3° east-southeast of Regulus, in Leo, and two nights later, it is 3.3° south-southeast of Mars.

Mercury

During the first week of July, Mercury puts on a good show in the west-northwestern sky after sunset, visible for 90 minutes past sunset on the 1st, and reaching its greatest elongation of 25.9° east of the Sun on the 4th.

Turning a larger telescope to the innermost planet reveals its tiny crescent, and on the 2nd, it will be within 1.0° southwest of the open cluster M44, the Beehive.

Mercury becomes difficult to observe by mid-month, so try to get a view of Mercury’s crescent phase through a telescope before it dips too low later in the month. It reaches inferior conjunction on the 31st, and becomes visible again in the morning sky during the second week of August.

Venus

Venus is still putting on a good show in the morning sky. Moving eastward through Taurus, it rises about 2.5 hours before sunrise. The brilliant planet is within a binocular field of Uranus all week, passing as close as 2.4° south-southeast of the seventh planet on the 4th.

Venus appears near the Hyades cluster during the second week of July, providing an impressive view in binoculars. On the 13th, Venus is closest to the bright star Aldebaran, which will be 3.2° to the south of it.

Earliest Venusrise occurs at 2:35am on the 15th.

The crescent Moon is 7.6° above the brilliant planet on the 21st.

On the 26th, Venus is located close to Tianguan (zeta Tauri). Turn your telescope to Venus and find M1, the Crab Nebula, just 0.5° north of the brilliant planet’s gibbous globe. 

Finally, for two days beginning on July 29, Venus passes through the non-zodiacal constellation Orion, crossing through the extreme northernmost segment marking the tip of the hunter’s club. It then crosses into Gemini, where it will be within the same binocular field of view of the open cluster M35, from which it will be just 2.4° south-southeast of on the 2nd. 

Mars

Crawling eastward through Leo, Mars is losing its prominence as an evening planet. At the start of July, tt sets less than three hours after sundown, and has faded to just a bit dimmer than Regulus, but remains slightly brighter than Denebola, the two brightest stars in its host constellation.

The Red Planet is over 2 au distant beginning on the 12th, and its diminutive globe is less than 5 arcseconds across, making its surface details very difficult to observe.

Mars becomes a resident of Virgo on the 28th. While it is still brighter than many of its surrounding stars, you’ll need a clear western horizon to continue to observe it, as it is only with us for about two hours after sunset in late July.

The 5.7% illuminated crescent Moon lies 3.3° to its east-southeast on the 26th.

Jupiter

Jupiter rises within an hour of sunrise, and remains difficult to view in early July. Later in the month, the giant planet begins to come into view low in the east-northeast before sunrise.

The waning crescent Moon is 8° directly above (northwest of) Jupiter on the 21st, and its slender 2.6% illuminated crescent is 4.6° to the northeast (left) of Jupiter on the 23rd. 

Jupiter rises before the onset of astronomical twilight by the end of the month.

Saturn

Saturn becomes an evening planet in July, rising before midnight beginning on the 7th.

Now that Saturn is well above the horizon during hours of darkness, transits of the shadow of its largest Moon, Titan, are more readily visible for us. A favorable one occurs on the 2nd, beginning at about 3:30am. Titan’s umbra, or inner shadow, is less than one arcsecond, so steady seeing and a large telescope will improve chances of a successful observation. Planetary imagers will also want to give these a try.

Watch for subsequent shadow transits at 16-day intervals through October 6, after which Titan’s orbital plane is too far offset from Saturn’s ecliptic plane for the shadow to intersect the globe of the planet. 

The distant planet Neptune lies just to the north of the ringed world. Although the two planets have different apparent motions, with Saturn moving more swiftly than Neptune, they will remain quite close to each other throughout the year. Their closest appearance occurs on the 6th, when they are separated by just 1.0°.

Saturn reaches its stationary point, and begins its apparent retrograde motion on the 14th. It will continue to move westward until November 28.

A second transit of Titan’s shadow on Saturn’s cloud tops begins at about 3:00am on the 18th.

The 69% illuminated waning gibbous Moon is 2.4° south of Saturn on the 19th.

Uranus

2025 is an exceptional year to observe our solar system's two outermost planets, Uranus and Neptune, not due to any special circumstances of their individual appearances, but because of their positions in close proximity to brighter, easy to locate objects.

First is Uranus, in Taurus, which is now within the same binocular field of view as the Pleiades cluster. From the Pleiades, move southward by 4.3° to find 13 and 14 Tauri, a pair of 6th magnitude stars separated by ⅓° that are oriented roughly west-to-east. Continue following the line connecting these stars eastward and slightly north, about 1.3°, to find the magnitude 5.8 pale blue-green orb of Uranus. At the end of the month, the distance spans to 2.4°.

On the morning of the 4th, Uranus lies in a line between Venus and the Pleiades, with Uranus 2.4° north-northwest of Venus.

On the morning of the 8th, a line drawn from Aldebaran, through Venus, leads directly to Uranus.

Uranus is closest to the Pleiades cluster, just 4.1° to its north-northwest, on the 15th.

Neptune

Neptune is in Pisces and is very easy to locate due to its position just 1.0° north of Saturn.  

The waning gibbous Moon is 1.5° north-northwest of Neptune on the 16th. Use a wide-field telescope or large binoculars to see the waning gibbous Moon, Neptune, and Saturn all in the same view.

Minor Planets

Ceres is moving eastward through Cetus. At the beginning of July, it shines at magnitude 9.0, and can be found 14° east-southeast of Saturn. On the 4th, use 25 Ceti as a guide, as the star is 0.5° north of the dwarf planet.

Ceres is within 2.5 au from Earth on the 26th.

Pluto is located in Capricornus, 8.5° south of Dabih (beta Capricorni) and 3.8° east-southeast of the globular cluster M75.

Pluto is at opposition on the 25th, at a distance of 34.299 au and magnitude 14.4. The New Horizons probe, which visited Pluto a decade ago, is now 27 au more distant.

Asteroid 2 Pallas remains near the high point of its orbit, and is well-placed for observing during July evenings within Delphinus. Its 9th magnitude glow can be seen 1.2° north-northwest of the globular cluster Caldwell 42 (NGC 7006) in early July. As the month progresses, it moves towards the familiar diamond asterism marking the body of the dolphin. On the 23rd, it is 0.4° north-northwest of the star marking the dolphin’s nose, gamma Delphini. On the 30th, it is 0.2° southeast of Sualocin (alpha Delphini).

At the end of July, Pallas shines at magnitude 9.4 from a distance of 2.51 au.

While Vesta is becoming more distant, passing 1.5 au on the 1st, its 7th magnitude shine remains within binocular visibility.. Early in the month, it is within 1.0° west of magnitude 5.40 106 Virginis. From there, it moves approximately 1/4° per day in a southeasterly direction away from Syrma (iota Virginis). It crosses into Libra on the 13th. On the 30th and 31st, it lies midway between mu Virginis and Zubenelgenubi (alpha Librae).

Asteroid 6 Hebe is in Aquarius and becomes binocular visible in July. It starts at magnitude 9.0, about 3.0° west-northwest of lambda Aquarii, and arcs southeastward through its stationary point on July 14, then continues moving southward as it brightens to magnitude 8.2 by the end of the month, when it lies 0.4° west of the face-on spiral galaxy NGC 7371, about 2.8° north-northwest of the magnitude 4.0 star tau Aquarii.

Meteors

Late July sees three meteor showers. The Southern delta Aquarids, a relatively low-rate showers whose origin is not yet know, with certainty, peaks on the night of the 29th-30th, when the 27.1% waxing crescent Moon sets early enough to not interfere with observations.

Peaking the same night, slowly entering particles from comet 169P/NEAT provide for an estimated ZHR of 5 for the alpha Capricornids.

Finally, although the peak doesn’t occur until mid-August, the Perseids are active from mid July. As the bright Moon will interfere with seeing this shower’s dust particles cast off from comet 109P/Swift-Tuttle, it may be worth being patient for the lower rates seen well before peak. 

Stars

A recent astronomical trivia event posed the question “Which of these constellations is not visible during July?” Among the choices were Pegasus, Pisces, Scorpius, and Gemini. The intended “correct” answer was, of course, Gemini, but at mid-northern latitudes, Gemini can indeed be observed during July. For the first few days of the month, generally up to the 4th, Castor and Pollux can be seen twinkling through twilight low in the northwest. Additionally, if you observe Jupiter any time this month, you’re looking at Gemini.

As darkness sets in, Arcturus becomes visible overhead, but notably west of the meridian. The great bear Ursa Major is oriented nose-down, with the familiar Big Dipper oriented in its summer position, pouring the contents of its bowl out high over the northwestern horizon.

Some of the bright galaxies of spring are still positioned high enough for viewing in the early evenings of July, but they’ll soon be out of sight as their host constellations Leo, Virgo, and Coma Berenices sink lower into the west as the month progresses.

The southern sky is dominated by Scorpius and Sagittarius, two constellations that contain some of the season's best celestial wonders, as well as the core of the Milky Way. Let’s take a look at two star clusters in Scorpius that are best seen on clear, moonless July evenings: Messier 6 and 7.

Located just a binocular field off the stinger of Scorpius, the pair of star clusters are easy to locate from locations with a clear southern horizon.

Messier 6, the more northern of the pair, contains about 120 member stars, and covers an area of sky slightly smaller than the full Moon. The cluster’s brighter members are said to resemble the shape of a butterfly, hence its nickname, the Butterfly Cluster. Of all the objects in the Messier catalog, M6 lies the closest, in apparent angular separation, to the center of the Milky Way – just 3.4°. Although the cluster appears visually close to the galactic center, its distance of 1590 light years puts it at only 1/16th the distance from our solar system to the middle of the Milky Way.

Travel 3.5° southeast to find the other cluster, Messier 7. Egyptian astronomer Ptolemy noted the presence of this cluster as a nebulous patch behind the stinger of Scorpius in about the year 130, making M7 one of the earliest discoveries of a nonstellar object that we now refer to as the deep sky. To credit his discovery, it has been given the nickname Ptolemy’s Cluster.

Containing about 80 stars sprinkled across an area just over 1.0° in width, M7 has a combined magnitude of 3.3, making it an easy object even under a bright sky. M7 holds the distinction of being the most southerly object in the Messier catalog.

Look overhead late in the evening to find the most prominent pattern in the summer sky, the Summer Triangle. The three brightest stars in the triangle belong to three different constellations. 

Altair, in Aquila, the eagle, is one of the closest stars to us, at 16.7 light years. It is a class A7 main sequence star about 1.7 times as massive as our Sun, and shining with about ten times the luminosity. Altair has one of the fastest rotation periods of any known main sequence star, about 10 hours, about the same as Jupiter. It rotates so fast that it is about 14% oblate.

Moving northward along the western edge of the triangle, we next find Vega, the brightest star in Lyra, the harp. It is a class A0 main sequence star located about 25 light years away. Vega has 2.3 times the mass of our Sun, 36 times its luminosity, and shines with a cool blue-white color at magnitude 0. At around 400 million years old, Vega is one of the youngest stars in our stellar neighborhood.

Moving eastward to Deneb, the most northern of the tree stars in the Summer Triangle, this star marks the tail feathers of Cygnus, the swan. Although only slightly dimmer than the other two stars in the triangle, Deneb is markedly more distant, about 1900 light years. Deneb is quite massive – the class A2 blue supergiant star is about 16 times that of the Sun, and radiates with over 50,000 times its luminosity, which allows it to be seen so easily from such a great distance. A very young star, at just over 10 million years, Deneb will eventually end as a Type II supernova.

While we’ve been anticipating the outburst of the Blaze Star, T Coronae Borealis, another nova has unexpectedly brightened in the southern constellation Lupus, the wolf. Designated V462 Lupi, or Nova Lupi 2025, it was discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN) on June 12, reached a peak magnitude of 5.5 in late June, and is expected to slowly fade. 

Lupus, the nova’s host constellation, may not be well-known to observers in New England, but there is a good chance you may have gazed at its stars on a dark spring night while exploring its more notable neighboring constellation to the northeast, Scorpius.

V462 Lupi lies at a declination of -40° 8’, about equal to that of the southernmost portion of the stinger of Scorpius, which clears our southern horizon by just 8°. This gives it both a very narrow window of visibility, as well as some notable constraints on being able to observe it. First, you will need a relatively unobstructed southern horizon, then you’ll need favorable weather, specifically, transparent skies, something July evenings are statistically unlikely to provide. Even on a perfectly clear and transparent night, an elevation of 8° corresponds to an airmass of 7, and a stellar object in this position has an extinction of two whole magnitudes.

Timing is also critical. Not only is the nova past the meridian and getting lower in the sky by the end of twilight, the waxing Moon introduces additional skyglow that will make a successful observation challenging beyond the first few days of July. By the time Moonlight is out of view, from the 13th and beyond, the nova lies at an elevation of less than 6° post-twilight, and likely will have faded significantly.

 At minimum, you’ll need a small telescope to begin the hunt. With low-to-medium power, locate the horizontal pair of stars gamma and delta Lupi, separated by 2.6°. Simply follow this line westward another 2.5° and you’ve reached the location of V462 Lupi.