Shallow Sky (Solar System) Section

Star trails

Section Director: Angus Burns
Activity areas: Sun, Moon, Planets, SatellitesAsteroids, Comets, Meteors, Occultations.
Specialists & Collaborators: Tim Cooper, Brian Fraser, Lee Labuschagne, Greg Roberts, Jim Knight
Section newsletter: Angus Burns (Southern Skies editor)
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9th August 2021

Bolide over the Western Cape

Several persons reported hearing sounds at around 1am on the morning of August 9. Locations included Riversdale, Mossel Bay, Oudtshoorn, Boggoms Bay, George, Hartenbos, Klein Brak River, Wilderness and De Rust, spanning a horizontal distance of around 115 km. The most westerly location where sounds were reported was Riversdale, where it was described as a rumble, like distant thunder. The most easterly was from several observers in the environs of George, where the sounds were mostly described as rumbling like thunder. From Oudtshoorn the sound was also likened to distant thunder. Others said it sounded like an explosion, houses shook and windows rattled.

Only three visual sightings were received of the bolide. The best description was received from Ted Nutting, who was outdoors at the time and saw the passage of a bright green fireball in a clear sky, duration about 4 seconds moving west to east, and disintegrated into four or five fragments with a bright flash before disappearing. Sounds were heard about two minutes later, as up to four distinct ‘bangs’ and tailing off afterwards like the sound of a jet flying over. Triangulation of the start and end points gives a tentative path from west to east, seen towards the north from George, but to the south from near De Rust, where the start and end azimuths were 230° and 180° respectively, traveling parallel to a rooftop, at altitude 60-70°. Frankie Dos Santos saw the bolide through a window facing azimuth 330° from Hoekwil, near Wilderness. He described the fireball as ‘very bright, much bigger than a normal shooting star’, moving left to right (towards north east) at an altitude of about 45°, and very fast with a duration of about a second. The sky was overcast with thin patchy clouds and the appearance was like seeing car headlights through fog. The bolide possibly began ablation near overhead and just south of Oudtshoorn, and disrupted in the vicinity above Kammanassie Nature Reserve. Fragments may have fallen as meteorites near to the Kammanassie Mountain range.

In order to determine the fall location of possible meteorites, sufficient video footage is required which shows both the passage and disruption of the bolide, or shadows cast by the flash, which are in the anti-direction of the disruption. Unfortunately, despite requests on various forums to check security cameras, only one clip was received, from Godwin Pangel in George. The clip shows a brief very bright flash, with duration less than 1 second, and was followed 2m56s later by a booming sound. The sky is seen to be mainly overcast at the time of the bright flash. The video footage was calibrated against internet time to give the time of the flash as August 9, 01:00:30 SAST. The time lag of the sound gives a distance to the flash of approximately 60km.

The event was not detected by NASA fireball detectors, neither were there any reports to the ASSA, AMS nor IMO reporting forums. I conclude that a bright bolide passed roughly west to east over the Western Cape, disrupting with a bright flash, and with accompanying sounds. Insufficient video evidence could be obtained that could have enabled determination of a strewn field site for meteorites.

Several misconceptions arose in the social media in connection with the event. Firstly the statement on some social media pages that the event was a ‘skyquake’. There is no accepted scientific definition of what constitutes a ‘skyquake’; rather it appears to be a loose term originating on the internet describing rumbling sounds from unexplained sources, including possibly the sonic boom from meteors. Since the bolide was observed visually, the suggestion that it was a ‘skyquake’ is clearly of no consequence.

Secondly that the event might be linked to the Perseid meteor shower, which normally peaks during the night of August 11/12, and showed an unexpected surge in activity this year on August 14 at 10am SAST, the outburst lasting about two hours. The August 9 event was not related to the normal activity or the outburst of the Perseids. The Perseid meteor stream is known debris from comet 109P/Swift-Tuttle, and particles from comets are too small to produce effects like that witnessed over the Western Cape on August 9. The radiant of the meteors in the constellation of Perseus only rises early morning and is highest before dawn, and even then the radiant does not rise above the horizon at any time as seen from the George/Mossel Bay area. Finally, the radiant is located in the north-east in the early morning and cannot explain any meteor observed on a trajectory from west to east.

Thirdly the misconception that what was seen was a meteorite. Particles travelling through space are termed meteoroids. If they enter the atmosphere then the resultant streak of light is termed a meteor. Bright meteors are termed fireballs, and if seen to explode they are called bolides. If the object survives its passage through the atmosphere, reaches the ground and is recovered then it is termed a meteorite. Since no videos were obtained to triangulate the path and hence no fragments could be found on the ground, the event on August 9 is classified as a bolide.

Possible path of the August 9 bolide.  Yellow pins are locations where sounds were heard, red pins are locations of the three observers who actually saw the bolide, green pin is the location of the one video which caught the bright flash.

August 2021

We are pleased to announce the results of the conjunction photo competition.

1st Angus Burns
2nd Jaco Boshoff
3rd Percy Jacobs

Marc Klynhans of has sponsored the following prizes:

  1. Svbony 1.25″ 18mm SWA eyepiece (1st prize)
  2. Svbony 2x Barlow and Svbony 1.25″ to T-thread adapter (2nd prize)
  3. Svbony 1.25″ UV/IR cut filter and Svbony 1.25″ 0.6ND filter (3rd prize)

Congratulations to the winners!

Great Conjunction – 21 Dec 2020 – Photo by Angus Burns, Newcastle, KZN

Comet C/2020 M3 ATLAS

by Kos Coronaios

Comet C/2020 M3 ATLAS is currently in the constellation of Orion. At Vm +8 (11/11/2020), the comet is not visible with the naked eye or with binoculars (10 x 50), but is within reach of small to medium sized telescopes ( it was an easy target in an 8-inch f5 SkyWatcher).

Discovered by the ATLAS telescope system earlier this year (June 27, 2020), it makes its closest approach to Earth on the 14th November. The ATLAS telescope system developed by the University of Hawaii is an asteroid or comet impact early warning system. The comet reached perihelion, closest approach to the Sun on October 25th this year. At closest approach to us, it will be 53 613 439 km from Earth and will not return until the year 2159. The comet appears as a small fuzzy diffuse object and not star-like at all. A position change can easily be noted after observing for 60 minutes or so as it moves at 51 500 km/h while the nearby stars appear or seem to be fixed in their positions. Over a 24 hour period the comets movement is easily noted.

The two images were taken from Pearly Beach in the Western Cape around midnight on the 11th November.

Comet C/2020 F8 (SWAN)

by Kos Coronaios

Comet C/2020 F8 (SWAN) was discovered in images taken by the SWAN camera on March 25th 2020, aboard the Solar Heliospheric Observer (SOHO), I was fortunate to have a number of imaging/observing sessions before the comet moved to close to the horizon in the early hours of the morning to be visible from my location in Pearly Beach, Western Cape. These started from the middle of April, with the last session on the 5th May when proximity to the horizon as well as the Moon became problematic.

Analyzing the images from SWAN, Michael Mattiazzo, (Swan Hill, Australia), realized that they showed a new comet in outburst. The comet increased in brightness becoming a naked eye apparition towards the end of April. While Southern hemisphere observers have had the best seats from around mid April to early May, the comet is rapidly moving northwards and if the comet’s brightness increases or at least remains as is for the next few weeks, northern hemisphere observers and astrophotographers are in for a treat. Comet SWAN will make its closest approach to Earth on May 12 and reach perihelion on May 27.

Comet C/2020 F3 NEOWISE

by Kos Coronaios

This comet is a long period comet with a near-parabolic orbit discovered on March 27, 2020, by astronomers during the NEOWISE mission of the Wide-field Infrared Survey Explorer space telescope.

At that time, it was an 18th-magnitude object, located 2 AU (300 million km; 190 million mi) away from the Sun and 1.7 AU (250 million km) away from Earth.

NEOWISE is known for being the brightest comet in the northern hemisphere since Comet Hale–Bopp in 1997. It was widely photographed by professional and amateur observers and was even spotted by people living near city centers and areas with light pollution. While it was too close to the Sun to be observed at perihelion (03 July 2020), it emerged from perihelion around magnitude 0.5 to 1, making it bright enough to be visible to the naked eye. Under dark skies, it could be seen with the naked eye and remained visible to the naked eye throughout July 2020. By July 30, the comet was about magnitude 5, but binoculars were required near urban areas to locate the comet.

For observers in the southern hemisphere, the comet was visible from around the 26th July a couple of degrees above the northern horizon after sunset. At around magnitude +5 it was never going to be visible with the naked eye due to it’s proximity to the horizon shortly after sunset, but it was a reasonably easy target for binoculars as well as small telescopes by the first week in August. Currently at around magnitude +7 it is in the constellation of Virgo, moving into Libra by the end of September 2020.

August 2020

“Clyde’s Spot – The Video

Presentation by Clyde Foster, Section Director – Shallow Sky
An amateur astronomer’s contribution in today’s world of Planetary Science”.

Clyde’s Spot – Clyde Foster

Juno images from last Tuesdays Perijove flyby(PJ27) have been downloaded from the spacecraft and are being circulated, including some preliminary results showing the outbreak that I have been credited with detecting only 2 days before the flyby (currently being referred to as “Clyde’s Spot”). Given the timing, the fact that Juno is in a 53 day highly elongated orbit, and only able to capture a thin slice of Jupiter during flyby, it is a remarkable coincidence.

The images show fascinating structures within the storm system that is already causing excitement within the Planetary Science community.

Note: An “outbreak” is a plume of gas that erupts out of and above the normal upper cloud layers of Jupiter, and is most easily detected in methane wavelengths where they show as bright. Outbreaks are common in the North and South Equatorial belts, but are rare in the South Temperate belt region where this one is, hence the interest.

I have also included my “discovery” image, where the outbreak is seen as a bright spot just to the lower right of the Great Red Spot(which is also bright at this wavelength)

Jupiter – latest photo

  • The giant planet Jupiter is becoming visible in the east during the evening as it approaches opposition on 10 June. It will remain well placed for evening observation for the next few months. The cloud belts and famous Great Red Spot (a huge, long-lived, anti-cyclonic storm system) are detectable in relatively small telescopes, although larger telescopes, combined with modern day imaging techniques show substantial detail. This image captured from Centurion, Gauteng by Clyde Foster using Celestron 14” Edge HD telescope, ZWO ASI290MM camera.

Current and upcoming events

    • 2019 March 1 – Visible in our evening skies is C/2018 Y1 (Iwamoto). A near-parabolic comet with a retrograde orbit discovered on December 20, 2018 by Japanese amateur
      astronomer Masayuki Iwamoto. It passed closest to Earth on February 13, 2019. It is
      expected to reach a magnitude of between 6.5 and 7.5, visible in binoculars or a small telescope.  Imaged on February 22nd 2019 from Pearly Beach, Western Cape
      by Kos Coronaios.

Poor conditions, lots of haze and low level cloud moving in and out of the target area. No moisture at ground level but certainly up at altitude. Comet was not visible in the finder scope, camera viewfinder, live view, or in binoculars (12×50). Could not see it at the eyepiece probably due to the camera not 100% aligned with the OTA and did not want to move the scope during the short imaging session that I had. And then the clouds really rolled in! With the Moon heading towards last quarter I’m hoping for some good clear skies down here with some mag. observations to add.

  • 2016 September 16 – Penumbral Lunar eclipse. Note that as this is a penumbral eclipse, only the outer Earth shadow will cross the Moon and as a result the eclipse may not be obvious to the naked eye.
  • 2016 October 3 – Moon is near Venus in the evening sky
  • 2016 October 6 – Moon is near Saturn in the evening sky
  • 2016 October 8 – International Observe the Moon Night. ASSA is currently looking at various initiatives for this evening, including the possibility of live streaming.
  • Orionids Meteor shower. This meteor shower is typically active from 2 October until 7 November, with the peak meteor rate being observed about the 21 October and best between midnight and 4.00am. Unfortunately conditions are not good this year for observing this shower.

Recent Events

  • The partial eclipse of the Sun on Thursday,  September 01 2016. This was the only solar eclipse visible from southern Africa this year. In fact, it was visible from almost anywhere in Africa (except the very northernmost parts), and seen from central Africa and Madagascar it would be annular. This rare event was a wonderful opportunity to witness the solar system in action, as the Moon slid in front of the Sun. Using simple materials, the progress of the eclipse – which lasted more or less 2 hours – could be watched, shown to family and friends, and shared with the world. Further information is available on the ASSA Eclipse 2016 page
  • Conjunction of Venus and Jupiter August 27th 2016. The separation of the pair on the 28th August 2016, at 18:49 (SAST) was 15′ 07.2” (just over a quarter of a degree). At their absolute minimum, the two planets had a separation of 4′ (arcminutes) at 21:47 (SAST), but would have been below the horizon for South African observers at this point.
  • Past events are archived on the ASSA website archive.

Observing Guides

  1. How to observe the Sun.
  2. How to observe the Moon.
  3. How to observe the planets.
  4. How to observe satellites.
  5. How to observe asteroids.
  6. How to observe comets.
  7. How to observe meteors.
  8. How to observe occultations.

Recipients of 2016 ASSA Shallow Sky Awards

  • Observing Certificate (Solar and Sunspot): Richard Ford

Information about ASSA Awards and previous award winners can be found on the ASSA Awards page.