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3 January 2011
Last updated at 19:31 ET
By Jonathan Amos
Science correspondent, BBC News
Tuesday will witness the first partial solar eclipse of 2011.
People standing across a great swathe of the Earth's surface will see the Moon take a big bite out of the Sun.
For north Africa and much of Europe, the event starts at sunrise, whereas in central Russia and northwest China, the spectacle occurs at sunset.
Northeast Sweden should get the best experience. At 0850 GMT, near the city of Skelleftea, the Moon will cover almost 90% of the Sun's diameter.
Skywatchers will have to have a high vantage point, however, as both celestial bodies will be skirting the horizon at that time.
As is always the case for solar eclipses, the public is being warned to take great care.
Viewing the Sun's harsh light should only be done through protective equipment - proper solar glasses and solar telescopes, or through a pinhole projection system.
In many places, professional and amateur astronomy groups will be setting up safe observing systems. In the UK, for example, there are a series of events tied into the BBC's Stargazing Live programmes.
Partial solar eclipses occur when the Sun and Moon do not quite align in the sky as viewed from Earth, and the deep shadow cast by the smaller body passing across the bigger one just misses the planet.
Nonetheless, the phenomenon will result in a dip in light, depending on how big a chunk of the solar disc the Moon can obscure. This effect will vary from place to place and in time.
Northern Algeria will be the first location to witness the phenomenon at 0640 GMT. In European cities like London and Paris, the eclipse will already be underway as the Sun rises, with the Moon covering up almost 70% of our star by 0812 GMT in the British capital, and 65% of the solar disc by 0809 GMT in the French capital.
The further east the event tracks, the closer it gets to local sunset. Central Russia, Kazakhstan, Mongolia and northwest China will all observe an eclipsed Sun dive over the horizon.
LOCAL TIMES FOR SELECTED CITIES
CITY Eclipse starts Eclipse Mid-point Eclipse ends Coverage of the Sun Information courtesy of SkyandTelescope.com
London
sunrise
0812
0931
67%
Madrid
sunrise
0852
1006
47%
Paris
sunrise
0909
1030
65%
Rome
0752
0910
1038
61%
Cairo
0902
1031
1206
44%
Stockholm
sunrise
0942
1105
79%
Budapest
0805
0928
1058
70%
Istanbul
0908
1037
1212
63%
Tel Aviv
0909
1041
1216
47%
Moscow
1038
1204
1330
74%
Baghdad
1032
1204
1335
42%
Karachi
1404
1446
1525
3%
There are a number of ready reckoners on the web that will compute local circumstances for just about any place on the planet.
Although there are three more partial solar eclipses this year, for Europeans in particular Tuesday's event is the key one. They will not get another chance to see so much of the Sun being covered up by the Moon until 20 March 2015.
The next total solar eclipse is in November 2013 over the South Pacific.
Jonathan.Amos-INTERNET@bbc.co.uk
Online Business Consulting | Internet Business Consulting
People standing across a great swathe of the Earth's surface will see the Moon take a big bite out of the Sun.
For north Africa and much of Europe, the event starts at sunrise, whereas in central Russia and northwest China, the spectacle occurs at sunset.
Northeast Sweden should get the best experience. At 0850 GMT, near the city of Skelleftea, the Moon will cover almost 90% of the Sun's diameter.
Skywatchers will have to have a high vantage point, however, as both celestial bodies will be skirting the horizon at that time.
As is always the case for solar eclipses, the public is being warned to take great care.
Viewing the Sun's harsh light should only be done through protective equipment - proper solar glasses and solar telescopes, or through a pinhole projection system.
In many places, professional and amateur astronomy groups will be setting up safe observing systems. In the UK, for example, there are a series of events tied into the BBC's Stargazing Live programmes.
Partial solar eclipses occur when the Sun and Moon do not quite align in the sky as viewed from Earth, and the deep shadow cast by the smaller body passing across the bigger one just misses the planet.
Nonetheless, the phenomenon will result in a dip in light, depending on how big a chunk of the solar disc the Moon can obscure. This effect will vary from place to place and in time.
Northern Algeria will be the first location to witness the phenomenon at 0640 GMT. In European cities like London and Paris, the eclipse will already be underway as the Sun rises, with the Moon covering up almost 70% of our star by 0812 GMT in the British capital, and 65% of the solar disc by 0809 GMT in the French capital.
The further east the event tracks, the closer it gets to local sunset. Central Russia, Kazakhstan, Mongolia and northwest China will all observe an eclipsed Sun dive over the horizon.
LOCAL TIMES FOR SELECTED CITIES
CITY Eclipse starts Eclipse Mid-point Eclipse ends Coverage of the Sun Information courtesy of SkyandTelescope.com
London
sunrise
0812
0931
67%
Madrid
sunrise
0852
1006
47%
Paris
sunrise
0909
1030
65%
Rome
0752
0910
1038
61%
Cairo
0902
1031
1206
44%
Stockholm
sunrise
0942
1105
79%
Budapest
0805
0928
1058
70%
Istanbul
0908
1037
1212
63%
Tel Aviv
0909
1041
1216
47%
Moscow
1038
1204
1330
74%
Baghdad
1032
1204
1335
42%
Karachi
1404
1446
1525
3%
There are a number of ready reckoners on the web that will compute local circumstances for just about any place on the planet.
Although there are three more partial solar eclipses this year, for Europeans in particular Tuesday's event is the key one. They will not get another chance to see so much of the Sun being covered up by the Moon until 20 March 2015.
The next total solar eclipse is in November 2013 over the South Pacific.
Jonathan.Amos-INTERNET@bbc.co.uk
Online Business Consulting | Internet Business Consulting