The month of August offers incredible night sky events, weather permitting, of course.

The southwest monsoon season is in full swing this summer, compromising stargazing, but delivering much needed water to New Mexico. Photo taken July 6, 2021.

Saturn is in opposition to the Sun and closest to Earth on August 2nd. Jupiter’s opposition follows on the 19th. Both planets will be bright (Jupiter being the brighter of the two) and visible all night.

The Perseid meteor shower, one of the best showers of the year, peaks on the night of August 12th and pre-dawn of the 13th. With the waxing crescent moon setting around 10:30pm MDT, observing conditions will be perfect for viewing about a meteor per minute, weather permitting.

‘Stargazer’ watches a Perseid meteor explode as it slams into the Earth’s atmosphere. Photo taken August 12, 2020, Santa Fe, NM.

The Summer Milky Way is well-positioned for evening viewing on clear, dark nights. As darkness falls in early August, the Milky Way will span the sky from the southern to the northeastern horizons. By month’s end, it will have shifted a bit, reaching from the SSW to the NNE horizons, passing almost overhead. Darkness occurs about 40 minutes earlier than in early August, making the Milky Way visible earlier in the evening.

August Planets:

Mercury opens August behind the Sun. By month’s end, it’s visible during evening twilight in Virgo, setting an hour after the Sun. Since the ecliptic is tilted toward the southwest, Mercury doesn’t get very high during this evening apparition.

Venus begins the month easily visible in Leo. By the end of the month, it moves higher in the sky and shifts east, into Virgo, setting as night begins (about 9:05pm MDT).

Mars begins August near Regulus, in Leo, but it’s almost on the opposite side of the Sun from Earth and is thus faint and hidden in twilight glare all month.

Jupiter reaches opposition to the Sun and closest to Earth on August 19th. See ‘August Spotlight’ for further details.

Saturn reaches opposition on August 2nd and is visible all night in the constellation Capricornus. This month is the best time to view Saturn for the remainder of the year since it’s close to Earth and its rings are wide open.

Jupiter (the bright ‘star’ on the left) and Saturn (2:30 from Jupiter, above the horse sculpture) follow the Summer Milky Way into the night sky, as they both approach opposition in August. Photo taken July 8, 2021.

August Spotlight:

The planet Jupiter has attracted attention since humans began gazing at the night sky. It’s usually the second brightest object in the night sky, excluding the Moon (Venus is the brightest; once every 15-17 years, Mars can briefly outshine Jupiter).

Jupiter is exceedingly bright now because it’s almost at its closest distance to Earth. Opposition (the time when the Sun, Earth, and planet line up, with Earth in the middle) occurs on the 19th of August. At that time, Jupiter will shine in Aquarius at magnitude -2.9. The next few weeks offer our best chance to view Jupiter until it next reaches opposition in September 2022.

To the unaided eye, Jupiter shines like a brilliant white pearl, rising around sunset and setting around sunrise. A small telescope will reveal Jupiter’s four largest moons, called the Galilean Moons. These four large moons were discovered and determined to be satellites of Jupiter by Galileo Galilei, when he turned his new telescope on Jupiter in 1610. I find it rewarding to watch these moons nightly, since they slowly change position relative to Jupiter and to each other.

Jupiter and its four Galilean moons. Photo taken with a Canon digital camera and 600mm lens.

Ganymede, the largest of the four moons, is slightly larger than the planet Mercury. Calisto is smaller than Mercury, but much larger than Earth’s Moon. Io is about the same size as our Moon, while Europa is a bit smaller.

Since Jupiter orbits the Sun just beyond the asteroid belt, its gravity has captured a number of small asteroids that strayed too close to the giant planet. Currently, there are 79 known moons of Jupiter, all but the four Galilean Moons being small and beyond the reach of small telescopes.

Sometimes, Jupiter captures objects and gobbles them up. One well-observed instance occurred in the early 1990s, when a comet was gravitationally captured by Jupiter. The comet broke apart before colliding with the planet, leaving a series of black disturbances in Jupiter’s upper atmosphere.

The dark splotches in Jupiter’s atmosphere mark the sites where pieces of Comet Shoemaker-Levy 9 slammed into Jupiter’s atmosphere. The Great Red Spot is visible at the lower left. Photo by NASA Hubble Telescope and copied from scientificamerican.com.

If you look closely at Jupiter through a small telescope, you’ll notice that it’s a bit wider at the equator than it is at the poles. This is due to the rapid rotation of the planet. Even though Jupiter’s diameter is about 11 times Earth’s, it spins once on its axis (a.k.a., a day) in just under 10 hours, versus 24 hours for an Earth day. This rapid rotation causes Jupiter’s atmosphere to noticeably bulge at the equator.

You’ll also observe faint horizontal bands crossing the planet. These are cloud patterns at the top of Jupiter’s atmosphere, caused by the planet’s rapid rotation and high winds. While most of Jupiter’s atmosphere is composed of hydrogen and helium, the visible clouds at the top of the atmosphere are mainly ammonia. The dark colored atmospheric bands are called ‘belts;’ the lighter colored ones are ‘zones.’

Detailed photographs of Jupiter’s weather at the top of the atmosphere, taken with telescopes and satellites, reveal these belts and zones to be incredibly complex swirling patterns and colors. One atmospheric feature that can be seen in a small to medium-sized telescope is a reddish oval called the ‘Great Red Spot.’ The Great Red Spot is a storm that has been continuously observed from Earth for over 300 years.

A close-up of Jupiter’s dynamic atmospheric belts and zones, photographed by NASA’s Juno orbiter.

Some astronomers consider Jupiter to be a ‘failed star’ since its atmosphere is mainly composed of hydrogen and helium, similar to the Sun, but lacks sufficient mass and pressure for the process of atomic fusion to occur. While true, the planet developed from the accretion of rocks and ice, like other planets in the solar system, not the compression of gas and dust that leads to star formation, like the Sun.

Thus, the solar system’s largest planet shines by reflected sunlight, rather than by light produced by internal thermonuclear reactions. Regardless, Jupiter is a breathtaking sight, whether viewed with the unaided eye or a telescope. Enjoy observing the planet and its four largest moons while it’s close to Earth (a mere 365 million miles at its closest on the night of August 19th).

August Night Sky Events:

August 1-31: The Zodiacal Light is visible about an hour before dawn. The Zodiacal Light is sunlight from the not yet risen Sun reflecting off of interplanetary dust particles. Clear, dark skies are required to see this faint light.

Zodiacal light glows over Galisteo before dawn, June 30, 2020. Venus is rising in the center, below the Pleiades star cluster. Mars is the bright object in the upper right quadrant.

August 2: Saturn is at opposition to the Sun and closest to Earth, visible all night long in the constellation Capricornus.

August 8: New moon.

August 12-13: The Perseid meteor shower peaks on the night of the 12th and morning of the 13th. This could be a great shower this year since the Moon sets around 10:30pm on the 12th. At peak, the shower could produce in excess of 60 meteors per hour.

August 19: Jupiter is at opposition to the Sun, shining at magnitude -2.7, near the Capricornus-Aquarius border.

August 22: Full moon occurs at 6:02am MDT. Since this is the third of four full moons in a three month period, it’s known as a ‘blue moon’ (as in, “once in a blue moon”). Blue moons occur about every 2.7 years.

An almost full moon rises before sunset. Distant wildfires spewed small particles into the atmosphere, contributing to the Moon’s faded appearance and yellowish color. Photo taken July 22, 2021.

Here are some photos of the Moon taken over the last six days, as it progressed from the waxing gibbous phase to full to the waning gibbous phase.

Wednesday evening, July 21st: The waxing gibbous moon, 94% illuminated, broke through the clouds, about 20 degrees above the ESE horizon. Seen against the blue background of early twilight, you can see some relief in the craters along the sunrise terminator at the left edge of the Moon. The straw color was, in part, due to viewing the Moon through the denser atmosphere near the horizon; water vapor in the air, due to recent showers; and smoke particulates from distant wildfires.

Thursday evening, July 22nd: The Moon increased to 97% illuminated, as the sunrise terminator moved west. The dark oval crater, Grimaldi, can be seen just inside the terminator (its position is between 7 and 8 o’clock). Grimaldi’s invisible in Wednesday’s photo.

Friday evening, July 23rd: The full moon’s face is devoid of relief since the Sun is shining directly onto the entire visible surface, as seen from Earth. It’s early morning on the left side of the image; local noon at the center; and late afternoon on the right edge.

Saturday evening, July 24th: Now in the waning gibbous phase, the Moon played cat and mouse with the clouds along the ESE horizon. This photo was taken after dark, when the Moon had cleared the clouds that had massed along the ESE horizon. Notice that relief can now be seen on the upper right edge since the sunset terminator has now moved into view.

Monday morning, July 26th: Sunday night was cloudy, so I got up before dawn Monday and took some photos of the Moon in partly cloudy skies. This photo was taken around 6:30am MDT. Notice how the orientation of the Moon has changed since it’s now setting rather than rising. Also, now that the phase is well past full, you can see significant relief along the sunset terminator on the right — the sunlight is low on that section of the Moon and shadows abound. Despite the partly cloudy skies, the seeing (a measure of how turbulent the atmosphere is – turbulence degrades image clarity) was good to excellent, allowing for greater image clarity, as compared to the earlier photos.

MOON MOODS

During this period, the Moon exhibited different moods as it crossed the sky amidst monsoon clouds. Here are some of the moods created by the Moon.

Friday evening, July 23rd: A yellowish full moon rose in clear ESE skies. The scene filled me with a sense of awe. The photo was taken about 20 minutes after the Moon was exactly full.

Saturday morning, July 24th: The Moon was partially hidden by clouds as it began to set in the WSW. The scene reminded me of old horror movies. The only thing missing was the howling of our local coyotes.

Sunday morning, July 25th: The Moon seemed to sail behind a veil of cloud, lighting the landscape in an eerie half-light.

Sunday morning, July 25th: As dawn brightened, the color of the sky changed from dark to light blue and the Moon transitioned from stark white to pale yellow.

Sunday evening, July 25th: The waning gibbous moon rising behind a thin cloud cover reminded me of Halloweens past.

Monday morning, July 26th: The Moon and Jupiter made a nice pair in the sky. Jupiter was so bright (Jupiter’s closest approach to Earth is about three weeks away), that you could still see it (lower right) with the naked eye, several minutes after sunrise. At night, the Moon serves as a celestial lantern, illuminating the landscape with dim light. But, seen in daytime, the Moon serves no visible function, becoming an ornament in the sky.

Patience will be a virtue in the month of July since our night skies will likely be storm-laden much of the time.

Cloud-to-cloud lightning. Photo taken June 19, 2021.

This month, the summer Milky Way moves into prime time – easily viewed deep sky objects abound within it.

The Milky Way is visible all night in July. By the time dawn tinges the sky in the ENE, the Milky Way appears to dive into the WSW horizon. Photo taken July 1, 2020.

July Planets:

Mercury reaches its farthest apparent distance west of the Sun on July 4th. On that date, the solar system’s innermost planet rises in the ENE, near Taurus the Bull’s easternmost (lower) horn, about 4:35am MDT.

Venus dominates the western sky after sunset. On the first of the month, Venus is located near the Beehive Cluster (M44) in Cancer. On July 13th, Venus and Mars will be in conjunction, a mere 0.5 degrees from one another. On the 21st, Venus will pass 1.0 degrees from Regulus, the brightest star in Leo. By month’s end, the brightest planet will have traveled halfway across the constellation Leo, setting in the WNW near the end of twilight (about 9:40pm MDT).

Mars is now a second magnitude object and is falling deeper into the glare of evening twilight. It’s in conjunction with Venus on the 13th, separated by 0.5 degrees. On the 29th, Mars is in conjunction with first magnitude star, Regulus, separated by 0.6 degrees. Optical aid will be needed to pick the Red Planet and star out of the glare.

Saturn is a first magnitude object, visible for most of the night in July. Please see ‘July Spotlight’ for more information regarding the ringed planet.

Jupiter chases Saturn into the evening sky, brightening as it gets closer to Earth. In a telescope, the flattened disk of the planet (caused by its rapid nine-hour rotation) grows in size during July. Look for the atmospheric belts and Great Red Spot as the planet rotates during the night. I like to watch the dance of the four Galilean moons as they orbit Jupiter, changing position from hour to hour and night to night.

July Spotlight:

Now a first-magnitude evening object, Saturn rises just after sunset. On the first of the month, the ringed planet rises at about 10:15pm MDT in the constellation Capricorn. By month’s end, it rises about 8:15pm MDT, just a quarter-hour after the Sun sets.

Saturn (right of center, 3:30 from Jupiter) precedes bright Jupiter into the sky. Photo taken June 21, 2021.

Since ancient times, Saturn was known as one of the five ‘planetes’ – Greek for ‘wanderer.’ Saturn was observed to be relatively slow-moving, yellowish in color, bright, but not terribly so. The Romans named the planet ‘Saturn,’ after their god of agriculture and prosperity.

Notions of Saturn changed in 1610 (the year Santa Fe was founded as the capital of Nuevo Mexico) when Galileo Galilei pointed a telescope at the sixth planet from the Sun. What Galileo saw (or thought he saw) through his crude new optical instrument was a large disk, with two smaller disks, one on either side of the main body – a three body planet. Other astronomers saw a single, oval body. Several years later, Galileo observed Saturn and found that the two attendant bodies to the larger, middle body had disappeared.

In 1616, the planet’s attendants were back. Galileo sketched the planet, this time showing a main body with a ‘handle’ on either side, a dark space between the main planet and each handle. Confusion about the shape and composition of Saturn continued until the second half of the 17th century when Christiaan Huygens, a Dutch astronomer, proposed that the ‘handles’ were really a single, flat, solid ring that encircled the planet.

Today, we know that Saturn is a large gaseous planet with a core likely composed of iron-nickel and rock. Saturn is orbited by 82 known moons. Most of Saturn’s retinue of moons are small, but one, Titan, is the second largest moon in the solar system — larger than the planet Mercury. Titan’s the only moon in the solar system with a dense atmosphere and, with the exception of Earth, the only object known to support a permanent body of surface liquid.

The planet’s surrounded by a series of rings, mostly composed of ice particles, ranging from dust-sized specks to 30-foot chunks. The rings are about 70,000 miles wide, from the inner to the outer edges. The inner edge of the ring system orbits the planet about 4,000 miles above the cloud tops.

Despite the enormous spread of the rings, the rings are incredibly thin – less than 70 feet thick. If Saturn’s rings could be reduced to the size of a sheet of paper, the rings would be 100 times thinner than a comparable sheet of paper! Presently, Saturn’s rings are inclined toward Earth by 17 degrees, making them easily visible telescopically.

Saturn’s so far from the Sun that it takes 29.4 Earth-years to complete one orbit, making Saturn the tortoise of the five visible planets. The planet’s so wide that about 19 Earths could be placed side-by-side across its equator. Saturn’s rapid rotation (a day and night on Saturn lasts about 10.4 hours) causes the equator to bulge, making its appearance slightly oval when viewed through a telescope. The visible ‘surface’ of Saturn that we see is the top of Saturn’s atmosphere, which is banded by parallel atmospheric belts shaped by the planet’s fast rotation and strong upper level winds. Saturn’s yellowish color comes from ammonia crystals in its upper atmosphere.

Saturn and its ring system. Courtesy of Hubble/NASA.

If this spotlight peaked your interest, I encourage you to learn more about this uniquely beautiful planet that will be opposite the Sun and closest to Earth on August 2nd.

July Night Sky Events:

July 1: The pre-dawn zodiacal light is visible in the east all month. You must be an early riser to see this phenomenon since dawn begins about 4am MDT this month.

Zodiacal light (sunlight reflecting off of interplanetary dust particles) glows over Galisteo, June 30, 2020. Since the photo was taken less than two weeks after summer solstice, the zodiacal light is ‘bent’ toward the right. By the autumnal equinox, it will be more vertical to the horizon. Venus is just rising beneath the Pleiades; Mars is at the upper right; the Milky Way stands straight up on the left.

July 4: Mercury is at its farthest apparent distance from the Sun, visible in the dawn sky.

July 9: New moon.

July 23: Full moon occurs at 8:37pm MDT in the constellation Capricorn. Often called the ‘Buck Moon’ because male deer begin to grow their antlers in early summer, it’s also referred to by some Algonquin tribes as the ‘Thunder Moon’ in recognition of the thunderstorms that occur in summer. The Hopi people gave the July moon a name that translates to, ‘Raptor Moon.’

July 28-29: The Delta Aquariid meteor shower peaks on the night of July 28th and morning of the 29th. Under ideal conditions, 10-20 meteors per hour can be seen during the shower’s peak. While most meteor showers have short-lived peaks, the Delta Aquariid shower can remain near peak for a day or two on either side of the 28th/29th. Unfortunately, the waning gibbous moon will hamper late night viewing.

It was almost exactly a year ago when the naked eye comet named ‘NEOWISE’ graced the morning and evening skies of early summer.

A close up of Comet NEOWISE’s nucleus and coma, along with part of its tail. Photo was taken in July 2020.

Twice this week, I observed with the naked eye what looked like a comet in the partly cloudy western twilight.

Bright object pointing down toward the WNW horizon, about 9:15pm MDT on June 25, 2021.

The object wasn’t a comet, it was an atmospheric event that some refer to as a ‘Venus pillar.’ NASA says Venus pillars are rare occurrences. In fact, the phenomenon is so rare that it doesn’t have an agreed upon name, although ‘Venus pillar’ seems appropriate since it’s similar to a ‘Sun pillar.’

A Sun pillar (a.k.a., light pillar) is light from the Sun, located just above or below the horizon, reflecting off horizontal ice crystals floating in the upper atmosphere. The reflection results in a vertical shaft of light, slightly bulging at the Sun’s position. If the Sun is above the horizon, the Sun pillar can appear above and below the Sun. If the Sun is just below the horizon, the shaft of light will rise vertically above the horizon, from the point directly above the recently set Sun.

A Sun pillar stands over the Jemez Mountains. Photo taken in April 2021.

With this week’s unusually cool, moist weather, ice crystals formed in the upper atmosphere. On two occasions, the planet Venus was close enough to the horizon and bright enough to create a mini-light pillar, above and below the planet.

In the second photograph above (the ‘bright object’ photo), a thick cloud blocked the lower half of the Venus pillar, creating a comet-like effect. The two photos below show the Venus pillar in its entirety.

A Venus pillar seen on June 25th, around 9:30pm MDT. One could argue that this is a Sun pillar since the pillar is created by sunlight reflecting off of ice crystals in Earth’s atmosphere – the sunlight just happened to reflect off of Venus’ cloud tops first!

A second Venus pillar, seen on June 27th, about 9:40pm MDT. Note the gibbous phase of the planet. The pillar bulges a bit in the middle, then appears to taper at the tips like a candle flame.

In all my time watching the sky, I’d never seen a Venus pillar. Now, I’ve seen two in one week.

The Moon was officially full at 12:40pm MDT on Thursday June 24th. At that time, the Sun, Earth, and Moon were aligned, with Earth in the middle. Because the Moon was near perigee in its orbit around Earth (‘perigee’ is the term used to describe an orbiting object’s closest approach to the object it orbits), it appeared slightly larger than average – hence the misleading name, ‘supermoon.’

The term ‘supermoon’ was actually coined by an astrologer. But, there’s nothing super about a supermoon, at least from an astronomical perspective. In fact, you wouldn’t know you were looking at a supermoon, unless somebody told you so.

The media likes to use terms like ‘supermoon’ to generate interest and excitement. They called the January 2019 total lunar eclipse, the ‘Super Blood Wolf Moon’ because it was a) a supermoon; b) an eclipsed moon, in which the Moon appears reddish; and c) some Native American tribes refer to the January full moon as the ‘Wolf Moon’ because hungry wolves are said to howl more on cold winter nights.

Personally, I think the hype does astronomy a disservice since it encourages people to go out and look at the night sky, thinking they’re going to see something really different and exciting, but come away disappointed because the Moon didn’t fill half the sky or rise dripping in blood.

OK, back to this week’s supermoon. Because the Moon was full at about midday on Thursday, it appeared to be virtually full on both Wednesday and Thursday evenings. Wednesday evening was pretty cloudy, but I managed to photograph the Moon through a large rift in the clouds.

When the Moon is full, there’s little detail to be seen on the surface, due to the lack of shadows. The full moon is beautiful to the unaided eye, but doesn’t show much more than light and dark patches, even in a telescope.

The light patches are called the ‘lunar highlands’ – these are geologically old surface materials (mainly igneous rock), which are heavily cratered.

The dark patches are known as ‘lunar maria’ or ‘lunar seas’ – the result of lava flows. Because the lava flows are more geologically recent than the lunar highlands, the maria are lightly peppered with craters, as compared to the heavily bombarded highlands. Many of the lunar maria appear round – this is due to lava flowing into and filling ancient impact basins.

In the attached photo taken on Wednesday, about 16 hours before full, you can see a little bit of relief along the lower left limb since there’s a just a sliver of night at the very edge. The rest of the Moon seems flat and featureless, although the maria and highlands are obvious due to their differences in brightness and color.

One exception is the bright, rayed crater, Tycho, easily seen at the lower right. Tycho’s 53-mile-wide crater was formed about 100 million years ago – likely the result of impact with an asteroid. Ejecta from the impact was blown across the surface of the Moon, creating the bright rays we see today. The longer rays are over 900 miles long.

The Moon, photographed on Wednesday night, about 16 hours before full.

Contrast Wednesday’s photo of the Moon (above) with the photo taken on Thursday, about ten hours after full (below). The lower left limb is now devoid of relief; the only visible surface detail is along the upper right limb. This is due to the fact that the Moon is now waning (past full). The sunrise terminator we saw before full has now moved beyond the visible portion of the Moon. But, the sunset terminator is now beginning to stretch along the right edge.

The Moon, photographed Thursday night, about ten hours after full.

Finally, check out the photo of the Moon below, taken Friday, about 35 hours after full moon. The sunset terminator has shifted to the west, compared to the Thursday photo, and the waning gibbous moon has taken on a slightly oval shape. Relief is obvious now, with numerous, shadow-filled craters spread along the upper right limb. The terminator provides the contrast of light and shadow, turning seemingly uninteresting markings into stark, three-dimensional relief.

The Moon, photographed Friday night, about 35 hours after full. The bright eastern crater walls along the sunset terminator at the upper right catch the last rays of the Sun, while the crater floors are filling with shadows created by the western walls.

The Moon, our closest neighbor, is often overlooked by those seeking planets and deep sky objects. It’s even seen as a nuisance, spreading light into the night sky, making it more difficult to view everything from star clusters and nebulae to meteors. I know the Moon is sometimes seen in a bad light (excuse the pun) because I sometimes fall into this trap.

But, the Moon is actually a never-ending source of interest and fascination, even in binoculars and small telescopes. If you focus on the terminator, you’ll see new features every night that may have escaped your eye the night before. So, embrace the Moon and marvel in its ever-changing face.