Archive for the ‘Astronomy blog’ Category

Daily cosmobite: Saturn at midnight

Published by Andrew Jacob on February 27, 2015 4 Comments

SaturnSaturn is the most beautiful celestial object to see through a telescope. Even after more than twenty years I still enjoy observing it. It is rising just before midnight at present.


Saturn. If you step back & squint this image most closely resembles the view of Saturn through a small telescope. NASA/JPL.





Free 30 minute astronomer-led tour of the new East Dome with its accessible telescope and exhibition ‘Revealing the Sky’ at 10am and 11am on 14th, 15th, 18th, 21st, 22nd March. The tour includes solar viewing (weather permitting) and a 3D Theatre show ‘Extreme Places’.  Its an opportunity to really enjoy one of the most interesting sites in NSW. Bookings required via Online bookings or phone our bookings officers on 9921 3485.

This is an official NSW Seniors Week event.

East Dome

Enjoying our new East Dome building! Photo T.Stevenson

The East Dome project was supported by the Department of Disability and Ageing. 

Additional information

The Millers Point bus runs regularly to the bottom of Sydney Observatory.
Meter parking is available on Observatory Hill. Limited parking for disability sticker visitors is available at Sydney Observatory (Please give your registration number when you book).

A good idea is to also visit our neighbours on Observatory Hill: the National Trust Cafe for morning tea or lunch and the SH Ervin Gallery to view their exhibition (entry fee charges apply). Gallery and Cafe visitors can park at the National Trust, a 2 minute walk from Sydney Observatory.

East Dome

Volunteers with MAAS conservator, Tim Morris, (far left) very proud of the restored astrograph! Photo T.Stevenson

Saturday 28 March
7:30pm to 10pm. BOOK NOW
See the stars shine brighter than ever as Sydney turns off its lights in support of the annual Earth Hour.

Prior to the lights off see an astronomy presentation. Tea and coffee will be available for purchase. The focus for the evening is viewing through telescopes and the planet Jupiter, the constellations Orion and the Southern Cross are amongst the many splendours of the night sky on show. In inclement weather we will recreate a dark starry sky in the digital planetarium.

Lights will go out from 8:30 to 9:30 when Sydney Observatory will be the perfect location to both view through telescopes and experience the heritage site as it was in a bygone era.

BOOK NOW or phone: 9921 3485.

Quetelet.Moon.IAU.GPNToday the Moon is at first quarter in the constellation Taurus. Look due north after sunset.



Quetelet, the only lunar crater beginning with ‘Q’. Map provided by the IAU Gazetteer of Planetary Nomenclature.





Saturday 14 March 2015, 5pm to 8:30pm
This seminar is open to all.
Cost: $10*
Held at Sydney Observatory this is an opportunity to hear great speakers focus on the contributions of amateur astronomers. Seminar cost includes refreshments. Numbers are limited so reserve your seminar seat today by emailing: *Note: Tickets to the dinner held on the previous evening include the cost of the seminar.

5pm Introduction by Sydney City Skywatchers President, Mike Chapman

5:10pm Keynote presentation by Professor Wayne Orchiston
‘John Tebbutt and the Formation of Sydney’s Earliest Astronomical Societies’

John Tebbutt. Collection MAAS.

Wayne Orchiston was born in New Zealand, but grew up in Sydney. In 1959 he joined the NSW Branch of the British Astronomical Association, and eventually served as President and he was later elected an Honorary Life Member. Wayne’s early observational interests were in sunspots, meteors, the planets and variable stars, but he also developed a passion for the history of Australian astronomy and particularly the achievements of the Branch’s first President, John Tebbutt of Windsor. Wayne has B.A. Honours and Ph.D. degrees from the University of Sydney and formerly worked at the CSIRO’s Division of Radiophysics, Sydney Observatory (part-time), Victoria College (later Deakin University, in Melbourne), the National Observatory of New Zealand (as Director), the Anglo-Australian Observatory and the CSIRO’s Australia Telescope National Facility (in Sydney), and finally James Cook University (Townsville) before joining the National Astronomical Research Institute of Thailand (NARIT) a little over two years ago, where he is a Senior Researcher. He is co-founder and Editor of the Journal of Astronomical History and Heritage, and in 2013 the IAU named minor planet 48471 Orchiston after him.
Sydney City Skywatchers are very grateful to the Donovan Astronomical Trust for helping fund Professor Orchiston’s visit to Sydney.

6:10pm Refreshments and discussion

6:30pm Sydney City Skywatcher presentations (15 mins each):
• Monty Leventhal OAM, Steavenson Award winner, ’22 years of Solar Observing’.
• Dr Nick Lomb, IMAgine Award winner, ‘Closing Encounters: the BAAs attempt to save Sydney Observatory’.
• Toner Stevenson, PhD candidate, ‘Women in Amateur Astronomy’
• Harry Roberts, Mike Kerr medal & McNiven Award winner, ‘Astronomical Illustration’

8pm Concluding remarks

8:30pm Optional dinner at the Hero of Waterloo
(not included in seminar cost)

Daily cosmobite: Mercury ushers in sunrise

Published by Andrew Jacob on February 25, 2015 No Comments

mercury.color.MessengerMercury is at “greatest elongation west” today, i.e. at its furthest apparent distance from the Sun. This means it is easiest to see just before sunrise. Look for the last ‘star’ visible in the morning twilight, it will be almost a handspan above the eastern horizon.

Mercury, messenger of the gods, heralds sunrise at present. This image from the Messenger spacecraft, NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.




Daily cosmobite: Dark observing locations in Adelaide

Published by Andrew Jacob on February 24, 2015 No Comments

iss-adelaide-nightLight pollution is the bane of city-based astronomers. This series of night time images was taken from the International Space Station. They help identify dark sites from which to best view the sky. This week we  look at Adelaide.

Adelaide at night as seen from the International Space Station. Image by Chris Hadfield.

Daily cosmobite: A “solar rose”

Published by Andrew Jacob on February 23, 2015 No Comments

SunRose_bbso_1152In October 2014 Big Bear Solar Observatory (BBSO) took an image of a sunspot. It was processed by Alan Friedman into this spectacular “solar rose”. Find out more at APOD (Feb 17, 2015) and see the original image at the BBSO gallery.


Sunspot 12177 in H-alpha light on October 2, 2014.  Big Bear Solar Obs.NJITAlan Friedman (Averted Imagination)





Daily cosmobite: Mars and Venus meet up in the west

Published by Andrew Jacob on February 20, 2015 No Comments

MarsNearVenusAndMoon.Feb21.2015From Feb 20-23, 2015 Mars and Venus will appear close in the evening sky. They are at their closest at 7-am on Feb 22 at just one Moon-width apart (or half a degree). The Moon itself, fresh into lunar new year,  is nearby on Feb 21 but not visible. Look for the Moon on Feb 22 when it is to the right and above the two planets. Venus looks white and much brighter than faint, orange-coloured Mars so a pair of binoculars may be helpful.


Look west on Feb 20,21,22 & 23 to see Mars and Venus close. Look about a fist width above the horizon at 8:15pm AEDT.


The twin peaks of lunar crater Pythagoras. Sketch and copyright Harry Roberts ©, all rights reserved.

Regular lunar observer Harry Roberts reports on his view of crater Pythagoras – a big crater seen in a small telescope.

            There’s much to be said for small ‘scopes: they sit on their tripods just waiting for something to happen!

In this case it was a good combination of lighting and libration on crater Pythagoras, in the Moon’s far northern latitudes – a spectacular glimpse of the crater’s interior and its complex of central peaks, with the terminator just 6 degrees west of the site! But heavy cloud loomed: no time for ‘big’ ‘scopes – the 100/1000 ‘Mak’ was pointed and sketching began a minute or two later.

This big crater, 130km wide, dates from the Eratosthenian period, 1.1 to 3.2 b.y ago. A wide time range: other epochs have ½ b.y or less, but Eratosthenian’s were formed over a two b.y. period. It looks younger rather than older, with bright central peaks and distinct collapse formations well preserved on its inner walls. Surprisingly, it seems there are ‘ponds’ of impact melt just beyond its NE rim: and even more surprising, it seems I logged one in the small ‘scope (Fig)!

What particularly caught my eye was the superb shadow, cast by the central peaks, which stretched 40km or so, to cast an ‘inky’ print on the lower slopes of the crater’s NW wall: a very pretty sight (Fig)!

The crater floor was dim and unevenly lit, due to unseen hummocks, low ridges, or both. And Orbiter images confirm shallow flooding in this crater, as it is so near the ‘far-side’ regions (where such flooding is rare). The bright central peaks seemed almost in contact, with a third hidden completely – and a bright ‘spur’ ran from the crater wall to the peaks on the N side (Fig), with a small secondary crater seen on the wall (arrow). While there is a scree of collapsed material from the wall on that side, it doesn’t reach the central peaks: perhaps I saw a floor ridge that also caught some rising sun. The Sun’s altitude at the site was just 7° at the time.

To the right the crater wall showed several scarps and terraces, looking a bit like Sydney’s coastline, each with a shadow between. Further right, distant rugged terrain was faintly seen: mangled regions where debris fields of huge craters have blended. It’s between that rough zone and the crater’s N wall that melt ‘ponds’ may be found (Fig, lower right). The inner walls on the left (W) side showed long bright scarps and some terraces cast thin shadows westward. The high (>4km) eastern walls (foreground) cast shadow across half the crater’s floor.

The terrain on Pythagoras’ east side (foreground, not drawn) is in fact the interior of ancient giant Babbage (broken line) – and ejecta from the younger crater is strewn over the latter’s floor in swirls.

Crater Pythagoras is co-temporal with well-known craters like Bullialdus, Eratosthenes and Theophilus (it’s bigger though) but shows what they might look like if seen from a low lunar orbit: it’s a revelation!

Pythagoras, the religious teacher and philosopher of 5thC BC Greece, was well known for his geometry, teaching that Nature expresses itself in ideal forms, which could be mathematically calculated (Wiki). This idea is pretty well accepted today, as is his theory that Earth was round and circled the Sun!  A most radical idea, however, even in the sixteenth century AD!

Keep the small ‘scopes ready: you can’t tell what might appear.

Harry Roberts is a Sun and Moon observer, a regular contributor to the Sydney Observatory blog and a member of the Sydney City Skywatchers.



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