Hot on the heels of yesterday’s total lunar eclipse, a partial solar eclipse will be visible from the UK on the morning of 4 January 2011. The next solar eclipse visible from the UK will not be until 20 March 2015.
The partially-eclipsed Sun will rise in the south-east a little after 08.00 and the eclipse will end around 09:30. The greatest eclipse will be seen from northern Sweden at 08.50.
The table below shows details of eclipse times and magnitudes for various UK cities:
Eclipse details courtesy of Fred Espinak (NASA)
The best viewing locations with longest viewing time, greatest obscuration and greatest magnitude are in southern and eastern UK, declining towards the north and west.
Viewing the eclipse
WARNING: never look at the Sun directly through an optical instrument such as telescope or binoculars – it can result in permanent blindness. It is also dangerous to look at a bright Sun with the naked eye. Do not use sunglasses, polaroid filters, smoked glass etc to look at the Sun.
The safest way to view an eclipse is via optical projection, such as a pinhole projector. The following links from Exploratorium explain how to make two kinds of projector and also how to obtain safe filters:
Image: Partial solar eclipse, 3 October 2005, taken through a solar
filter. Mike Dryland, Flamsteed Astronomy Society
21 December 2010 – UK viewers will be able to catch the start of a total lunar eclipse this morning, the first for three years, with totality starting at 07.41 GMT and lasting a little over an hour. Within the UK, Scotland and Northern Ireland will get the best views.
Lunar eclipses occur when the Moon passes through the Earth’s shadow. During eclipse, the Moon may turn blood red or pink, with indirect sunlight giving the Moon a ghostly hue. Find out more in our eclipses fact file.
The last time a total lunar eclipse occurred on the winter solstice was in 1638, and the next time will be in 2094.
20 December 2011 – At 23.38 UTC (GMT) tomorrow, 21 December, the solstice will occur. In the Northern hemisphere it’s the winter solstice, in the Southern hemisphere the summer solstice.
At the solstices the Sun is at its furthest from the celestial equator (the projection of the Earth’s equator onto the sky). The world ‘solstice’ comes from the Latin solstitium meaning ‘Sun stands still’ because the apparent movement of the Sun’s path north or south stops before changing direction. At the winter solstice, the apparent position of the Sun reaches its most southerly point against the background stars.
Shortest day and sunrise/sunset times
The winter solstice also marks the shortest day (and longest night), but not the earliest sunrise or latest sunset. The earliest sunset occurred on around 12 December 2010 (15:51 in London) and the latest sunrise will occur around 30 December (08:06 in London).
The reason for this is the slight variation in the length of ‘natural’ days throughout the year, resulting from a combination of the Earth’s elliptical orbit around the Sun and the tilt of the planet’s rotation axis. For clocks to work all days need to have an equal length, which is therefore fixed at the average length of a natural day (hence the ‘mean’ in Greenwich Mean Time). This has a knock-on effect on sunrise/sunset times, and the earliest sunrise occurs several days before the longest day and the latest several days (about 9) after the shortest.
Opinion is divided over whether the solstice marks the start of winter or the middle of winter, or whether winter actually starts on 1 December (as reckoned by most meteorologists).
Marking the solstice
Under the early Julian Calendar, the winter solstice occurred on 25 December. When the more accurate Gregorian calendar was introduced in 1582, the solstice slipped to the 21st, but the Christian celebration of the birth of Christ has continued to be held on 25 December. This date is also associated with the Roman Saturnalia festival, and ‘Dies Natalis Solis Invicti’ (the birthday of the unconquered sun), as well as Nordic pagan festivals.
Solstice shorts: Yuletide stargazing
For an alternative way to celebrate the solstice, why not join us for our 25-minute Yuletide stargazing sessions, daily at 16.30 and 17.00 on 20-23 December? These offer a unique opportunity to look through our historic 28-inch diameter refracting telescope, and to view one of the more striking double stars.
Places are limited and tickets are £6 per person. You can book online or call 020 8312 6608 between 10.00-16.00. (Please note: If adverse weather conditions prevent viewing through the telescopes, an alternative programme will be offered. We are not able to offer refunds under such circumstances.)
Whichever way you choose to celebrate this time of year, we hope you will enjoy yourselves and have a very happy festive season!
It’s a seasonal staple of carols, Christmas cards and nativity plays but what was the Star of Bethlehem? Astronomical fact or pious fiction, theological symbolism or astrological sign, or simply an inexplicable supernatural event?
The truth is of course that nobody knows for sure, but there are some more and less convincing theories.
The star according to Matthew
Only Matthew’s gospel mentions the star and the Magi or wise men, in the following passage:
After Jesus was born in Bethlehem in Judea, during the time of King Herod, Magi from the east came to Jerusalem and asked, “Where is the one who has been born king of the Jews? We saw his star in the east [or at its rising] and have come to worship him.”… Then Herod called the Magi secretly and found out from them the exact time the star had appeared… After they had heard the king, they went on their way, and the star they had seen in the east [or at its rising] went ahead of them until it stopped over the place where the child was. When they saw the star, they were overjoyed.
(Matthew chapter 2, verses 1-2, 7, 9-10, New International Version)
From this we gather that the star first appeared or rose at a particular time, that it apparently moved (‘went ahead of them’) and stopped, and that to the Magi at least it signified the birth of a ‘king of the Jews’.
Astronomically, it’s been suggested that the star may have been a nova or supernova explosion; a comet; a triple conjunction of Jupiter and Saturn; a close grouping of the three planets Jupiter, Saturn and Mars; a stationary point of Jupiter; or a variable star (one whose brightness changes over time).
Chinese records mention a possible nova or comet in 5BC – an unusually bright star which appeared in the eastern sky for 70 days, and which may have been a nova outburst from the variable star DO Aquilae. This occurred at about the same time as a triple conjunction of Jupiter and Saturn in the constellation of Pisces. The rare combination of these two events may well have been seen by the Magi as a religious sign.
It’s likely that the Magi studied astrology, so the star’s astrological aspects are probably at least as important as its astronomical explanation. Rutgers astronomer Michael Molnar has suggested that a double
occultation of Jupiter by the Moon in Aries in 6BC could have astrologically
signified the birth of a divine ‘king of the Jews’.
Others of couse think that the writer of Matthew’s gospel simply invented the star, perhaps to fulfil the Old Testament prophecy that ‘A star will come out of Jacob; a sceptre will rise out of Israel’ (Numbers chapter 24, verse 17). More likely is that Matthew’s star is simply an example of ‘Midrash’ – an established Judaic tradition of theological writing in which non-factual elements can be used to bring out the religious meaning of the factual account. So whether or not there actually was a star is less important than the spiritual message Matthew is trying to convey.
We can’t know for sure whether, what or when the star was. But perhaps the answer is not either/or out of the alternative strands of explanation – astronomical, astrological, theological, supernatural – but both/and. It’s plausible that the Star of Bethlehem was a genuine astronomical event – perhaps a nova associated with a variable star – that had astrological significance to the Magi and theological significance to Matthew.
Whatever the truth is, we wish you a very happy Christmas!
Note: this post is an edited re-posting from last Christmas, based on our fact file about the Star of Bethlehem.