TELESCOPE HOUSE AUGUST SKY GUIDE
Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.
Telescope House August 2022 Sky Guide
For those of us in the temperate Northern Hemisphere, true darkness begins to return during August - making deep sky observation and imagining considerably more practical than they have been during the lighter parts of May, June and July. While those inhabiting locations above 55 degrees N will have to endure permanent astronomical twilight for a little longer, the earlier parts of August for many inhabitants of Europe, North America and Asia will see true darkness returning before midnight and lasting for three hours. By the end of the month, this period of darkness will have roughly doubled to around six hours - quite a difference.
For readers in the Southern Hemisphere, the advent of August means Midwinter is long gone and darkness is slowly receding. No matter where you are on our planet, there’s plenty to see in the skies above us this month…
The Solar System
Our natural satellite starts August as an evening object, almost due west in the sky in Virgo at sunset. At around 15% illumination present thin crescent standing around 16 1/2° high (from 51° north). The Moon continues tracking through the expansive Virgo, during the next few days, into the southerly constellation of Libra, where on 5th August it is to be found at half phase.
The second week of August finds the Moon tracking through the extreme south of the Ecliptic. It moves through Scorpius, Ophiuchus, Sagittarius and on into Capricornus, where it meets Saturn, just before becoming Full on the evening of the 12th. Naturally, this point of the month will be the worst for observing and photographing deep sky objects. Unlike last month, this month’s Full Moon will not be a so-called “SuperMoon”. However, the low height of the Moon in the sky from the northern hemisphere, coupled with atmospheric lensing will doubtless make the Moon appear impressively large, when rising or setting. As we often point out, Full Moon is actually the worst time to observe the Moon through a telescope as the direct sunlight at lunar “noon” tends to bleach out features and lack of relief and shadow detail makes observation of common features quite difficult. Moon filters for telescopes can help a little when the Moon is Full, but it’s really at Crescent or Gibbous phases when the Moon is at its best.
The Full Moon and Saturn in Capricornus, early morning 12th August. Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.
After reaching Full, the Moon continues to climb the northerly ascent of the Ecliptic plane through Aquarius, Pisces and Cetus, where it meets the very prominent Jupiter on the Pisces/Cetus borders on the 15th.
On the 18th, the Moon occults Uranus, though sadly this event will not be seen from Europe - the Moon having set just before the event takes place.
The Moon reaches Last Quarter phase in the constellation Taurus, on the 19th. It will join the brightening Mars in reasonably close conjunction during the early morning hours, having risen just before midnight (BST). The two objects are just approaching the Meridian and the highest point in the sky, as the Sun rises on the 19th.
Cresting over the top of the Ecliptic and rapidly decreasing its phase as it does, the Moon passes through Gemini, Cancer (where it meets the prominent Venus, on the morning of August 26th) and on into Leo where it becomes New, joining the Sun on the 27th of August.
The last few days of August finds the Moon re-emerging as an evening target, passing Mercury in western Virgo on the evening of the 29th and ending the month at 19% illuminated Evening Crescent phase in the eastern reaches of the constellation.
Mercury can be found at the beginning of the month in the constellation of Leo. Separated from the Sun by a little over 16°, the innermost planet of the solar system is not especially high in the sky from higher northern latitudes (just over 6° elevation at sunset, from 51° north), but at -0.6 magnitude should be prominent enough to find just after the Sun goes down, if you have a clear westerly horizon. The planet presents a 5.3 arc second diameter disc, 85% illuminated, at the beginning of August.
The first week of August finds Mercury gaining separation from the Sun, though this does not come with increased elevation, when viewed from temperate northern locations - the planet being in an area of the Ecliptic inclined distinctly further towards the horizontal, from these parts of the world. Those who observe Mercury from closer to the equator will fare distinctly better as far as altitude goes.
By mid-month, mercury will have faded a little too around +0.0 magnitude, now displaying a larger 6.1 arc second diameter desk, but at only 69% illumination. The planet sits no higher in the sky at sunset from midnorthern latitudes, that it did at the beginning of August. But again, those in the equatorial regions of our planet will be treated to a rather spectacular separation from the horizon, at around 24° elevation.
Mercury, sunset, 15th August Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.
The second half of August finds mercury retaining its brightness, though fading a little towards the end of the month. The planet reaches maximum eastern elongation on August 27, when it can be found over 27° from the Sun. By this point, it will have started to drop in altitude at sunset, from northern locations - sitting just over four degrees high in the sky (from 51° north).
Venus will be very prominent at sunrise in the mornings during August. On the 1st, it can be found in the constellation of Gemini, at -3.9 magnitude, displaying a 10.7 arc second diameter disc, illuminated by just under 93%. At an altitude of just under 16° elevation (from 51° north), Venus is not ideally situated for telescopic observation, but should be rewarding enough to turn a telescope in the direction of, should you be up early enough.
By the middle of the month, not much has changed as far as Venus is concerned. Now a resident of Cancer, the planet remains static at -3.9 magnitude and now displays a 10.4 arc second diameter disc. Venus is currently heading sunward from our perspective here on Earth and at this time is separated from our parent star, by just over 18°.
Venus, sunrise, 15th August. Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.
By August’s end, Venus has moved into the constellation of Leo and can now be found at an altitude of just below 12° at sunrise (from 51° north). The planet is still -3.9 magnitude and has largely retained its diameter, now displaying a 10.1 arc second disk. The planet still has some way to go until late October’s Superior Conjunction, but the window for easy observation of Venus is definitely closing.
The Red Planet is to be found in Aries at the beginning of August. At +0.2 magnitude and displaying an 8.3 arc second diameter disc, it is not especially prominent, but certainly brighter than any star in its resident constellation. The 1st finds Mars in reasonably close conjunction with Uranus, with the two planets separated by just under 1 1/2° from each other. You will have to be up reasonably early in the morning to observe this, but if you do, Mars will provide convenient signpost for the match fainter outer world.
Mars and Uranus, 1st August. Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.
By the middle of August, Mars has moved across the border into Taurus. The 15th finds the planet at +0.1 magnitude and displaying a 8.9 arc second diameter disc. Mars will rise at a little before midnight and transits at a little after dawn the following morning.
The end of August finds Mars having broken through to minus magnitude figures - but not by much. The 31st finds Mars at -0.1 magnitude, now displaying a 9.7 arc second diameter disc. The planet at this point is found in between the higher D’s and Pleiades star clusters in Taurus, with Mars appearing very similar in brightness and hue to Alpha Taurii, Aldebaran. It will be interesting for early risers to compare the two in such close proximity to each other.
As previously stated in preceding sky guides, the trend is definitely upwards as far as Mars is concerned, though we still have some way to go until early December’s Opposition, when the Red Planet will be distinctly brighter and much larger. However, for observers in the northern hemisphere, Mars is now in a very reasonable area of sky for observation, being just shy of transiting as the Sun rises on the 31st.
Much closer to Opposition, is the planet Jupiter, which reaches its brightest and closest to Earth, in late September. The first of the month finds Jupiter a brief resident of the non-zodiacal constellation of Cetus, shining and a bright -2.7 magnitude and displaying a disc of just over 45 arc seconds diameter. Rising at just before 11 pm on the 1st, Jupiter will be best-seen in the early morning sky, transiting at just after 5 am.
Jupiter has just started its retrograde motion in the sky, which is a certain sign of impending Opposition. The planet is (of course) not moving backwards in its orbit at all, rather we are catching it up on our faster interior orbit and Jupiter is as a consequence, appearing to move backwards in relation to background stars. This will continue until November, from which point, it will resume its “proper” motion in the sky.
Come mid-month, Jupiter will increase brightness to -2.8 magnitude, now displaying a disc just under 47 arc seconds diameter. Jupiter can still be found in Cetus, now rising at just a little before 10 pm and transiting at just after 4 am the following morning.
At the end of August, dubitable of Brighton and just a little again 2-2.9 magnitude and is now displaying a 48.7 arc second diameter disc. The planet rise a little before 9 pm and transit at just after 3 am the following morning. Still found in the non-zodiacal constellation of Cetus, Jupiter will only be a resident of this constellation for another day after this point, where after it will resume its residency of neighbouring Pisces.
There are some interesting mutual transit events to note on Jupiter this month. On the morning of August 2, there is a Great Red Spot and Ganymede and Io transit, which will be best seen a little around 4 am (BST). There is another similar event, a week later, on the morning of August 9, peaking at around 5 am. There is another Great Red Spot, Io and Ganymede double shadow transit event, at just before sunrise on 16th of August. There is a dual Great Red Spot and Europa transit at around 1.30 am on August 24. There is another dual Great Red Spot and Europa transit at around 3 am on August 31.
Jupiter, Great Red Spot, Ganymede and Io Transits, 4am 4th August. Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.
The jewel of the solar system, Saturn, reaches Opposition on August 14th. Now a president of Capricornus, Saturn is better placed for observation for those of us in the northern hemisphere than it has been for many years. While it still hasn’t broken through the magic 30° elevation for many observers above mid-northern latitudes (above which, seeing conditions improve significantly), Saturn’s continuing rise in the Ecliptic, as seen from the northern hemisphere, is cause for celebration.
At the beginning of August, Saturn presents 8+0.4 magnitude, 18.7 arc second diameter disc. The planet rises at a little before 9:30 pm (BST), transiting a little after 2.15 am the following morning.
By Opposition night, Saturn will have brightened fractionally to +0.3 magnitude, now displaying an 18.8 arc second diameter disk. By this point in the month, the planet will rise a little after 8:30 pm and transits just before 1:30 am the following morning.
Saturn and major Moons, Opposition night, 14th August. Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.
Binoculars will reveal more of Saturn’s pale yellow colour and show it as elongated. Magnification of at least 20-25x will be needed see the ring. However, most observers tend to need at least 45x magnification to see Saturn as a definitely “ringed” object, with the ring distinct from the the planet itself - with good seeing naturally playing a big part in this. More magnification and greater aperture will revel the true beauty of the ring system, which was first glimpsed by human eyes back in 1610 by Galileo. Back when he first observed Saturn, the planet was sitting in a very similar part of the sky in Capricornus and came to Opposition on the 13th of August, so conditions for observation in Europe this year are extremely similar - though the ring plane was slightly more closed in 1610 than it appears now. Galileo’s telescope, which he first turned towards Saturn was very small, with very primitive lenses and a modest magnification of 20x and yet he was an astute enough observer to recognise that Saturn wasn’t simply a disk. Although he was later to define what we now understand as a ring, at first he thought the planet was displaying “ears” either side of its tiny disk. Later observations showed these ears had disappeared, when the Earth crossed Saturn’s ring plane and the ring later reappeared as it opened up again, by which time Galileo had a slightly more powerful instrument at his disposal and presumably better seeing conditions, with the planet climbing higher north within the Ecliptic. His sketch of 1616 shows Saturn as we would reasonably expect in a small telescope, though it was to be the best part of four decades, in 1655, until Christiaan Huygens equipped with a yet more powerful telescope observed, recorded and described Saturn’s ring as such - also discovering Titan, Saturn’s largest moon in the same year. We cannot blame Galileo for not recognising Saturn’s ring for what it was - considering how new the telescope was as a piece of technology and how limited our then understanding of the solar system. But it was observing Saturn’s rings, Jupiter’s moons and the phases of Venus which showed Galileo that the planets were not immutable and unchanging as had been previously thought, but very much “living” changeable bodies. It was these first observations which started a complete revolution in science and the way human beings see their place in the universe and as such, helped to shape the modern world we live in - all from a tiny refracting telescope.
With the continuing narrowing of Saturn’s ring plane to us, as seen from Earth, along with the orbital plane of many of its major Moons, we can now witness transit events of Enceladus, Mimas and Tethys - although these are much, much more challenging events to observe in the telescope than those of Jupiters Galilean family of Moons, requiring significant telescopic aperture and compliant atmospherics to do so.
At the end of August, Saturn will still be +0.3 magnitude, though has shrunk a little from Opposition’s peak, back to 18.7 arc seconds diameter.
Uranus and Neptune
As previously mentioned, probably the highlight of August for the two outer planets is Uranus’ conjunction with Mars in Aries on the 1st August. Both Uranus and Neptune, while reasonably-sized worlds are a long way away, considerably fainter and as a consequence, much more difficult to find in the sky than all of the other major planets. Having a nearby brighter planet to act as a signpost, helps finding either of the outer worlds considerably.
At magnitude +5.8, Uranus is on the boundaries of naked eye visibility, from a reasonably dark site. However, most observers will need at least binoculars to make a positive identification of it. Mars’ proximity to Uranus on the 1st of August is a real help in doing so.
Neptune is much more difficult to observe and it +7.8 magnitude is way beyond the limits of naked eye visibility. A resident of Pisces, the bright planet Jupiter in neighbouring Cetus, can be found approximately 13 1/2° to the east of Neptune and at least gives the observer a rough guide to the area of sky the outer planet can be found in. Once found, Neptune is a rich blue colour, which is evident in the eyepiece of binoculars or small telescopes. Sitting under the five stars which represents the “head” of the more southern of the two “fishes” of Pisces, Neptune presents a challenge to observe, but is relatively straightforward to find at this time.
Uranus and Neptune relative sky positions, 1st August. Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.
Comet C/2017 K2 (PANSTARRS) Continues on its trick through the westerly reaches of Ophiuchus into the “head” of Scorpius, during August. As such, it will be visible in the early evening and will be approaching peak brightness during August (though this peak may continue for sometime). Heading south as the month progresses, for those of us in the northern hemisphere August really does represent the best time to catch this comet. Beyond the end of the month, the comet will really be the preserve of southern hemisphere observers only.
At time of writing, the comet is hovering around 7th to 8th magnitude. This puts it in reach of binoculars, but this comet emphatically is not a naked eye object. Catch this one while you can.
C/2017 K2 (PANSTARRS). Image created with SkySafari 5 for Mac OS X, ©2010-2016 Simulation Curriculum Corp., skysafariastronomy.com.
Vying with December’s Geminid meteor shower, the Perseids of August are the year’s most reliable display of meteors. Sadly, this year the Perseids will be heavily affected by the presence of the Full Moon, which will be present in the sky exactly concurrently with the shower’s peak. While this is a pity, the Perseids can be seen from mid-July, until early September, so while the peak of this year’s event will be washed out by the Moon, you are more than likely to see a Perseid to two, if you’re out during a more Moon-free night during August.