Illumination of the Earth during an equinox. Image Credit: http://en.wikipedia.org/wiki/File:Earth-lighting-equinox_EN.png
02:29 UT (03:29 BST) sees the Southward equinox. For ourselves in the Northern Hemisphere, it is known as the Autumnal equinox and the Vernal or Spring equinox for residents in the Southern Hemisphere. The Sun falls on the Celestial Equator during the Autumnal equinox resulting in equal lengths of day and night across the planet. From today on-wards as the name suggests, the Sun is seen to be moving southwards, resulting in shorter days and longer nights for us.
The Celestial Sphere. Image credit: http://www.kirchdorferweb.com
The point on the Celestial Equator where the Sun lies during the Vernal equinox is known as the First Point of Aries. However, due to precession (the continued change in the rotation of the planet on its axis), the Sun is no longer in the constellation of Aries and has not been since around 100 BC. At the moment, the Sun is in the constellation of Pisces and by the year 2600 it will be in the neighbouring constellation of Aquarius.
As the Sun rises at an equinox, the Sun will appear to cross the horizon due east and recrosses the horizon at Sunset due west. Over the next 3 months leading up to the Winter or December Solstice, the Sun will appear to rise and set further to the south of these points as it appears to follow the path of the ecliptic. It will then move back north approaching the northward equinox in March when the Sun will again rise and set due east and west respectively.
Posted in News
Tagged Aquarius, Autumn, autumnal equinox, celestial equator, celestial sphere, ecliptic, first point of Aries, northward, Pisces, precession, solstice, southward, Vernal equinox
Allosaur Skull of Hidden Horizons
SARAS were invited to be a part of the first Yorkshire Fossil Festival that was held in and around the Rotunda Museum in Scarborough between 12th and 14th September. A very busy weekend saw exhibitors including the Natural History Museum, Geological Society, Paleontological Association, local universities, Rotunda Geology Group and Hidden Horizons providing many hands-on activities for the weekend.
The society involvement for the weekend included answering peoples questions about the Sun, aurora, planets, our Milky Way and life in the Universe. A pair of telescopes were setup but unfortunately little Sun was visible through the cloudy skies.
Should a repeat be held in Scarborough, the astronomical society will certainly be hoping to attend again.
Society secretary Andy Exton FRAS visited Dalby Forest on Saturday 12th July to meet the cub scouts from Clifton Methodist in York. The initial plan was to do some observing from Adderstone Field but a thunderstorm resulted in the group relocating back to their camp on Moorcock Meadow and do some learning in their large communal tent – a metal framed tent in the middle of a large thunderstorm that one of the leaders informed me had been struck previously on another camp!
The group learnt about the Sun, planets and moons of the Solar System, constellations and how to find the pole star Polaris for navigation purposes.
A number of hands on activities aided their learning towards their astronomer badges which requires them to build a model and a small project after the camp to complete the award. The group were very well behaved and full of questions.
Posted in News, Public Outreach, Scouts / Guides
Tagged Adderstone Field, Andy Exton FRAS, constellations, Cubs, Dalby Forest, moons, Moorcock Meadow, Planets, Polaris, Sun
Prof. Sam Falle. Image credit: Leeds University
The June meeting of the society saw a talk on supernovae by guest speaker Prof. Sam Falle, Professor of Fluid Dynamics at the School of Mathematics at Leeds University.
Society treasurer Mell Jeffery FRAS writes:
Image taken by NASAs WISE telescope. SN 1572 is the red circular nebulae in the upper left. Image Credit: NASA/JPL-Caltech/UCLA
“Prof. Sam Falle started the evening by talking about historic supernovae and who observed and recorded them. Chinese astronomers made the first records of such events up until the Middle Ages when European records start, Tycho Brahe made the first European records (Tycho’s Supernova – SN 1572).
Observations prior to this had probably been made in Europe, but was cast aside due to religion as anything within the heavens was pure and only on Earth could things be subject to change and degrade!
He then went on to discuss the differing types (type I & II) and the differences between them, what changes occur for a star to go supernova, what happens during the event and afterwards – young, middle aged and old supernovae. References to the speed of the explosions were made in relation to ‘bombs’ of various types and their similarities!
It was a very interesting talk.”
The northern solstice. Image credit: http://commons.wikimedia.org/
Summer officially starts at 10:51 UT (11:51 BST) on 21st June in the northern hemisphere with the northern solstice.
The solstice occurs when the northern hemisphere of the Earth is inclined at a maximum angle (23° 26′) towards the Sun and results in the longest period of daylight. In fact, for residents within the Arctic Circle, 24 hours of sunshine occurs and for those on the Tropic of Cancer, the Sun will be directly overhead. After the summer solstice, the daytimes shorten and the nights become darker and longer (something astronomers look forward to).
The opposite occurs in the southern hemisphere that sees the winter solstice at this same time. The reverse of this event occurs with the southern solstice on Dec 21st 2014 at 23:03 UT.