Eclipse totale de lune, 21 février 2008 /Total lunar eclipse, February 21 2008
Originally uploaded by Laurence_
Last night’s eclipse has triggered a spate of activity on Flickr – total lunar eclipse was the most popular tag in the last 24 hours. We have picked out a few shots and saved them in our favourite photos, including the nice shot of the Moon against clouds above.
If you are interested in learning more about astrophotography, we are running a photography workshop on 4th March. Tickets are £15/£11 and must be booked in advance.
If, like me, you were clouded out last night, you can enjoy the lunar eclipse through the SpaceWeather.com gallery. The image to the left was taken last night by Mohammad Taher Pilevar, in Hamedan, Iran.
In the early hours of the morning of Thursday 21 February (the night of Wednesday 20 February) there will be a total lunar eclipse. The event will be visible from Western Europe (including the UK), Western Africa, all of South America, and central and Eastern parts of both the USA and Canada.
The times for the event are as follows:
- 00:30 GMT: The Moon begins to enter the Earth’s penumbral shadow at 00:30 GMT – you may not even notice this, since the Moon will only be slightly darker
- 01:43 GMT: The Moon begins to enter the Earth’s umbral shadow – this is when the full Moon begins to get really dark!
- 03:01-03:51 GMT: The entire Moon is now in the dark umbral shadow of the Earth, although some red sunlight will get through the Earth’s atmosphere and illuminate the Moon, giving it a deep red colour
- 03:51 GMT: The Moon begins to leave the umbra and enters the other side of the penumbra
- 05:09 GMT: The Moon has left the umbra behind, and is almost fully illuminated by the Sun again
- 06:20 GMT: Moon leaves penumbral shadow
But what are the penumbra and umbra shadows? Well, take a look at my tea mug to the left. As you can see, when I cast a shadow of the mug onto the desk using a lamp, there are two shadows – a lighter penumbra shadow, and a much darker umbra shadow. These two shadows are caused by the width of the light bulb (or Sun). If the light source was a tiny pin-point of light, there would only be one deep shadow.
As a taster, below is a time-lapse movie of a total lunar eclipse that occurred in 2006.
Click on the image for a time-lapse movie (format: Windows Media Player)
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Rocky planets, possibly with conditions suitable for life, may be more common than previously thought in our galaxy, a study has found.
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Two gas giant planets, similar to Jupiter and Saturn, have been discovered orbiting a star 5000 light-years away. The discovery suggests that giant planets are likely to be found in family groups.
Most sky-watchers will recognise the familiar sight of Orion, the constellation which is dominating our view of the night sky at the moment.
But how would Orion look if we had X-ray eyes?
Objects at different temperatures give off light at different wavelengths. We can see this on the thermometer below. People are far too cold to give off visible light – we emit infrared light instead. Unfortunately, our eyes are not sensitive to infrared light, which is why we cannot see each other in the dark.
We humans rely on light originating from objects at a temperature of 2,000-12,000°C – objects that emit visible light. At 5,500°C, the Sun gives off plenty of visible light, as does a light bulb containing a filament glowing at up to 3,000°C.
But there are some things in our Universe that are much, much hotter… at millions of degrees Celsius.
From stars falling into black-holes, to neutrons stars speeding through space at 300,000 miles per hour; from supernovae explosions colliding with interstellar gas, to white dwarf stars being bombarded with a thousand million tonnes of gas… every second.
All of these (and more) emit X-ray radiation.
The slideshow below cycles through the familiar visible view of Orion, to the unfamiliar X-ray view of Orion.
The X-ray view of Orion was put together by Konrad Dennerl & Wolfgang Voges at MPE in 1995, to celebrate 5 years of ROSAT. Rosat was a German/US/UK X-ray space-telescope, that operated from 1990-1999.
When comparing the two views of Orion, pay particular attention to:
- Orion’s belt, the Orion nebula, and Sirius – all of which are emitting both X-ray and visible light.
- The Crab nebula, which is very faint visually, but is very X-ray bright.
- The Moon and Betelgeuse – both are visibly bright, but X-ray faint.
- The star Sirius, which is a double star system, made up of the stars Sirius A and Sirius B. Sirius A is 10,000 times brighter than Sirius B to our own eyes, and so the visible image is dominated by light from Sirius A. However, Sirius B is a hot white dwarf star which emits lots of X-rays, and so the X-ray image is dominated by the light from Sirius B.
So the next time you gaze upon Orion, think how different it looks through X-ray eyes.
The Royal Observatory has a new program of spring courses for the general public. You can learn how to take photographs of the night sky at our astrophotography workshop, or learn about the Big Bang and black holes at one of our monthly lectures.
Download the full programme of courses and talks as a PDF leaflet.
The Space Shuttle Atlantis successfully docked with the International Space Station today – and you can see them fly overhead for yourself. The pair are astonishingly bright – all you need to do to see them is to look up at the right time!
You can see the space station rising in the West, flying over the South, before heading towards the East. It crosses the entire night sky in about 5 minutes. Remember – if it flashes, it’s an aircraft, but if it has a constant brightness, then you are looking at a satellite. To confirm that you have seen a satellite, keep watching to see if it suddenly disappears into the shadow of the Earth.
The following table gives the (approximate) times (within 1-2 minutes) when the International Space Station is flying over the UK for the next week.
10 Feb, 18:34-18:38 GMT, peak 74° high
11 Feb, 17:20-17:25 GMT, peak 85° high
11 Feb, 18:55-18:58 GMT, peak 44° high
12 Feb, 17:40-17:46 GMT, peak 78° high
12 Feb, 19:15-19:18 GMT, peak 23° high
13 Feb, 18:01-18:06 GMT, peak 48° high
14 Feb, 18:21-18:26 GMT, peak 25° high
16 Feb, 17:27-17:32 GMT, peak 28° high
If you live outside the UK, see Heavens-above.com for times when the space station can be seen flying over your location.
Here is a beautiful photograph of the 7 February solar eclipse, as seen from New Zealand. The photograph was taken by Andy Dodson and Deborah Hambly in New Zealand, where, as described in an earlier post, the Moon covered 59% of the Sun.
The photograph shows lots of activity around the limb of the Sun. These prominences are jets of hot gas, propelled outwards along the magnetic field lines of the Sun. Click on the image for a larger version.
For 84 years the major global news headlines of the day have been preceded by the six Greenwich Time ‘pips’. When the news of Neil Armstrong’s first steps on the Moon, President John F Kennedy’s assassination, and the destruction of the Berlin Wall were broadcast across the world on the BBC, they followed the familiar sound of the Greenwich pips.
The six-pip Time Signal was introduced on 5 February following the successful broadcast of the chimes of Big Ben to usher in the new year of 1924. Late in 1923, Frank Dyson, ninth Astronomer Royal, visited John Reith, Director General of the BBC, to discuss the idea of public time signals being broadcast. The six-pip Time Signal (pips for seconds 55, 56, 57, 58, 59, 60) was Dyson’s brain-child, devised in discussion with Frank Hope-Jones, inventor of the free pendulum clock, who had originally advocated a five-pip signal.
In 1939, the six-pip signal and the Time Service moved from Greenwich to the magnetic observatory at Abinger in Surrey. They then moved to Herstmonceux, Sussex in 1957. In 1990, the Greenwich Time Signal transmitted its last pips. Since then the BBC has originated its own pips based on signals from the GPS satellite network and from the 60kHz radio transmitter at Anthorn, Cumbria, operated by VT Communications under contract to the National Physical Laboratory.
The original clock used for the six-pips signal is in the Time and Greenwich gallery at the Royal Observatory. This is currently closed for redecoration, but will reopen on 1 March 2008.
The clock is regulator number 2016 by Dent of London. It was made in 1874 for use across the globe when observing the Transit of Venus astronomical phenomenon that year, before moving to Greenwich. It was the very first to provide the six-pip signals in 1924 with pendulum roller contacts, which are still in the Observatory collection.
