Archive for 2014

Daily cosmobite: when does the year start?

Published by Nick Lomb on December 31, 2014 3 Comments

31_Janus_Wikimedia CommonsIn England during the Middle Ages 25 December was taken as the start of the year. In the late 12th century the start of the year was shifted by nine months to 25 March. The official start of the year only became the familiar 1 January in 1752, the year in which England adopted the Gregorian Calendar.

The first month of the year January is named after Janus the two-faced Roman deity for beginnings and transitions. Courtesy Wikimedia Commons

Daily Cosmobite: A time ball to usher in 2015

Published by Andrew Jacob on December 30, 2014 No Comments

Sydney Observatory time ballSydney Observatory’s time ball has been in operation since 1858. It will drop at exactly midnight on New Year’s Eve to usher in the new year. If you are nearby look for the time ball on top of our tower – when it drops 2015 begins. Happy New Year!

 

The time ball at Sydney Observatory in mid-drop. Photo © MAAS, Sydney.

Daily Cosmobite: Sydney Observatory Conservation Plan

Published by Andrew Jacob on December 29, 2014 No Comments

Sydney Observatory Conservation Plan 2002The Sydney Observatory Conservation Plan (revised edition of 2002) has, for many years, been a guide for MAAS staff when considering both conservation and development plans for the Observatory site. It also forms an essential reference to much of Sydney Observatory’s history. We are pleased to say it is now freely available.

Brenan Dew is  usually a guide at Sydney Observatory but he is currently overseas as a part the Macquarie Theban Tomb Project along with several of his colleagues from Macquarie University, excavating and recording the tomb of an official by the name of Amenmose who lived in the Ramesside period of ancient Egypt, some 3300 years ago. Brenan visited the mortuary temple of Hatshepsut at Deir el Bahari at sunrise on the winter solstice and on Christmas Day. You can read Brenan’s winter solstice post and here is some background to the famous tomb from Wikipedia.

Today’s post is a Christmas greeting from Brenan. Brenan’s ‘selfie’ (taken with a tripod) gives you a good idea of the size and scale of the temple. You can find out more about astronomical heritage, and many other interesting locations, on the UNESCO World heritage and International Astronomical Union site. You will find Sydney Observatory is listed. I hope you enjoy Brenan’s photo of his Christmas day expedition as much as I did.

Brenan Dew

Brenan Dew, Christmas Day in Egypt at the temple of Hatshepsut at Deir el Bahari. Photo B. Dew.

 

 

Today’s Cosmobite is by Sam Knox, an astronomy guide at MAAS – Sydney Observatory.

December 27th 1571 marked the birth of the mastermind behind the laws of planetary motion, Johannes Kepler. His three laws described the motion of all the planets around the Sun and consolidated Copernicus’ Sun centered, or heliocentric, solar system. Kepler’s laws linked how the speed of a planet is described by its elliptical orbit. These laws, as described in Astronomia nova, Harmonices Mundi and Epitome Astronomiae Copernicanae, also provided the foundations for Isaac Newton’s theory of Universal Gravitation.

Kepler

Kepler’s second law of planetary motion. Credit: Gonfer

early-telescopes-1600s-early-1700s-jena-opticshes-museum

Early telescopes on display at Jena as the astronomer Johannes Kepler looks on, image Melissa Hulbert

This special Boxing Day 2014 Cosmobite is prepared by Brenan Dew, Sydney Observatory guide, archaeologist and cultural astronomy researcher.

Hello! My name is Brenan and I am usually a guide at Sydney Observatory. However, I am currently overseas as a part the Macquarie Theban Tomb Project where I am spending two months, along with several colleagues from Macquarie University, excavating and recording the tomb of an official by the name of Amenmose who lived in the Ramesside period of ancient Egypt, some 3300 years ago.

Several days ago on the morning of the December solstice I was able to combine my two passions of Egyptology and Astronomy when I ventured to the famous mortuary temple of Hatshepsut at Deir el Bahari to watch the sun rise. But this is no normal sunrise. On the morning of the December solstice the sun rises directly in line with the main axis of the temple, it shines through the door on the upper terrace and illuminates the inner sanctuary, and I was in the right place at the right time to see it! I stood with my camera poised, practically alone within the temple, and managed to capture some amazing shots.

Hatshepsut at Deir el Bahari © Brenan Dew.

Entry to the mortuary temple of Hatshepsut at Deir el Bahari. Photograph taken during the summer solstice, 2014 © Brenan Dew.

 

The first image (above) is the view looking through the doorway in the direction of the rising sun and the second was taken when I turned around, looking into the inner sanctuary of the temple.

Grand temple of Karnak © Brenan Dew.

Upper terrace of the mortuary temple during the summer solstice, 2014 © Brenan Dew.

As this second image shows, the sunlight that comes through the door on the upper terrace does not exactly line up with the inner sanctuary as it would have when this temple was originally built. This is not due to the effect of procession as I first thought, but this slight variation is caused by minor changes in the obliquity of the ecliptic. That is, changes in the Earths axial tilt that occur on a very long timescale, means the sun does not rise in exactly the same position today as it did when the temple was built almost three and a half thousand years ago. Nonetheless, this event was a truly remarkable one to experience.

I was lucky enough to be in Egypt for the December solstice of 2012 and at that time I visited the grand temple of Karnak, which is also aligned to the rising sun of the December solstice! These events highlight the importance of astronomy within this ancient culture, and that the ancient Egyptian people must have paid close attention to the skies to both notice the sun when it reached the solstice and to align their buildings to this once a year event. I highly recommend anyone travelling through Egypt at the right time of year to get up early and visit either of these temples for this incredible solstice event, it is one you will never forget!!

PS: previously this blog was titled ‘Summer’ solstice- thanks to all who picked this mistake (made by T. Stevenson) up!>

January 2015 night sky guide podcast, transcript and sky chart

Published by Sydney Observatory on December 24, 2014 1 Comment

Dr Nick LombTo help you learn about the southern night sky, Sydney Observatory provides an audio guide/podcast, transcript of that audio, and a sky map or chart each month. This month’s guide is presented by Dr Nick Lomb (pictured at right), Sydney Observatory’s Curator of Astronomy.

Nick takes us on a tour of the stars and constellations prominent in the January sky, including Betelgeuse and Rigel in Orion, Aldebaran in Taurus, and Sirius, the brightest star in the night sky, in the constellation Canis Major. In the evenings in January, you should be able to see the bright planet Jupiter, Venus, Mars and, briefly, Mercury. In the mornings Jupiter and Saturn will be visible, with the gibbous Moon near Jupiter on 8th, and the crescent Moon near Saturn on 16th January.

For this and more, listen to the January 2015 night sky guide audio, or read the transcript below.

HEAR THE AUDIO
You can subscribe with iTunes or upload the (20 mins 51 secs) audio to your iPod or mp3 player, or listen to it on your computer.

SEE THE SKY CHART
We provide an embedded sky map (below) and a January 2015 night sky chart (PDF) which shows the stars, constellations and planets visible in the night sky from anywhere in Australia. To view PDF star charts you will need to download and install Adobe Acrobat Reader if it’s not on your computer already.

January 2015 night sky chart

BUY THE BOOK
Our annual book, ‘The 2015 Australasian sky guide’ – this year the 25th anniversary edition – by Dr Nick Lomb has more information and star maps for months from December 2014 until December 2015 inclusive, plus information about the Sun, twilight, the Moon and tides, and a host of other fascinating astronomical information. You can purchase it ($16.95) at Sydney Observatory and Powerhouse Museum shops or other good bookshops, or online through Powerhouse Publishing (additional packing/postage costs apply).

READ THE TRANSCRIPT (after the jump)

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Daily Cosmobite: Comets

Published by Toner Stevenson on December 22, 2014 No Comments

Today’s Cosmobite is by Sam Knox, an astronomy guide at MAAS – Sydney Observatory.

Comets have been in the news a lot this month. We have seen incredible images taken from the surface of comet 67P/Churyumov–Gerasimenko by the incredibly nimble lander Philae and from Rosetta, Philae’s orbital companion. European Southern Observatory (ESA) engineer, Dr Warrick Holmes, visited Sydney Observatory in December 2014 and presented to senior school students an illustrated lecture about the Rosetta Mission and why comets are important to study.

Comets

Dr Warrick Holmes with his model of comet 67P

Dr Holmes is an Australian, born in Adelaide, and he has been part of the Rosetta mission from the beginning.

Recently some incredible images of the ferociously green comet 2014/Q2 (Lovejoy) which is fast approaching the inner solar system at about 35-km/s which is just faster than crossing the English channel in one second.

But what is a comet? A comet is like a huge, dirty snow ball that orbits the Sun, but not like the planets. Their orbits are usually far from circular and when they get close to the Sun they spray gas and dust into space creating two or more distinguishable tails. Comets come from either the Kuiper belt, which is just beyond the orbit of Neptune or the Oort Cloud which reaches out from the Sun at 0.8 light years in every direction. These comets can start falling towards the Sun due to a gravitational tug from a large planet or two comets colliding. At this point, the comets will begin their long voyage towards the Sun heating up and ejecting gas and dust as they get close. These comets can take an incredible 6 million years to orbit around the Sun and their death reminds us of the story of Icarus who flew too close to the sun – they ‘melt’ until they disappear.

Comet 2014/Q2 (Lovejoy): Damian Peach

The Christmas Comet, 2014/Q2 ( Lovejoy) high in the southern sky. Credit: Damian Peach

Daily cosmobite: the Great Nebula in Orion

Published by Nick Lomb on December 21, 2014 No Comments

26_Great Nebula in Orion_NASAThe constellation called ‘Orion’ is currently prominent in the night sky from around 9pm in Eastern Australia. An area of the constellation is said to represent Orion’s ‘belt’, also known by some Australians as the ‘Saucepan’.  The middle ‘star’ of Orion’s dagger, or the ‘handle of the Saucepan’ is not a star at all, but a huge cloud of gas and dust. Located about 1500 light years from us, it is a region where new stars are forming. Through a small telescope it is one of the most spectacular sights in the sky at present.

The Hubble Space Telescope’s panoramic view of the Great Nebula in Orion. Courtesy NASA,ESA, M. Robberto (Space Telescope Science Institute/ESA) and the Hubble Space Telescope Orion Treasury Project Team

The first successful rendezvous in space, of the Gemini 6A and Gemini 7 spacecraft, was in December 1965. This marked the beginning of many space rendezvous and demonstrated the potential for two spacecraft to dock in orbit.  The two craft were not equipped for docking but came within 1 foot (or approx. 30cm) of each other, which is very close!

Today’s Cosmobite is by Sam Knox, an astronomy guide at MAAS – Sydney Observatory.

Gemini 7

Gemini 7 from Gemini 6A, in low Earth orbit. Photo courtesy NASA.

 

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