Astronomy
Under a Red Moon at Dawn
Update, 2008 Feb 25:
Eclipse report – some impressions of the total eclipse
Posted 2008 January 14 @ 00:39 - filed under Astronomy.
On Thursday morning, 2008 February 21, just before sunrise, a huge blood-red Moon low in the west will greet the dawn. This total lunar eclipse is the last one visible from southern Africa until 2011.
Thursday's eclipse will be visible from most parts of the world: from anywhere in Africa (except Madagascar), most of Arabia, all of Europe and the Americas, and the western parts of Russia.
From southern Africa, the main part of the eclipse starts on Thursday morning at 03:43, when the Earth's curved orange/red-coloured inner shadow crosses over the Moon. At 04:20, half of the Moon is eclipsed. At 05:00, the Moon is fully eclipsed, and remains completely covered until 05:51, when it begins to emerge as the curved shadow moves off. With the sky already brightening with daybreak, the Moon sets, while still partially covered in shadow.
Setting the scene: Wednesday evening
On Wednesday evening, February 20, as the Sun is setting in the west, the Full Moon is already a short way above the eastern horizon, having risen 20 minutes earlier. If buildings, trees or mountains cut off your eastern horizon, keep a lookout until you see the bright yellow lunar orb moving very slowly upward – you're actually witnessing our Earth turning. This is a great opportunity from some creative photography.
Forty minutes or so after sunset, the sky will be dark enough to spot two bright stars near the Moon. Both lie below and to the right of the Moon. Nearest the Moon (3° away, or six lunar-diameters) is the star Regulus, the heart of Leo the Lion. Lower down and further right of Regulus (6° away) lies Saturn, the brighter of the two lunar companions.
Closeup on Saturn
This majestic planet, famous for it's beautiful rings, is much larger than our Earth – our entire world would fit quite comfortably in the gap between Saturn and it's closest ring, as the diagram shows. On the other hand, Regulus is much larger than Saturn – as the second diagram illustrates (which includes the Sun, for comparison). Regulus is also much further: Saturn lies "only" 1 billion km from Earth, while Regulus is some 730,000 billion km away!
Although you can't see it, the Earth's shadow extends outward into space, in a direction midway between Saturn and Regulus. The two are rushing towards each other and when they meet, it's eclipse-time, as the Moon moves along it's orbit around our planet and into the shadow.
Looking around the early-evening sky, the most prominent figure is Orion the Hunter, high up in the north. To Orion's upper-right is the brilliant star Sirius, brightest in the night sky. The brightest star below Orion, about half-way down to the horizon, is the orange-red planet Mars.
Facing south, you'll find Crux (the Southern Cross) and the two Pointers low in the south-east. The long arm of Crux points upward across the sky to the bright star Achernar. High above Crux lies a larger cross-shaped pattern, the False Cross. Dozens of star clusters and nebulae can be seen in this part of the sky in binoculars.
From several centres, bright satellites will be visible during the course of Wednesday night/Thursday morning. From all over the country, the International Space Station makes a flyby shortly after 5 in the morning while the eclipse is in full swing – imagine the view the astronauts must have! Capetonians will see an Iridium satellite flare to –1 magnitude with a three-quarters eclipsed Moon in the sky, whilst from Sutherland, a magnificent –8 magnitude flare adds lustre to the scene. Further details appear in the tables at the end of this article.
Midnight onward
By midnight, the Moon, Regulus and Saturn are high up in the north. Notice how much closer the Moon and Regulus are. Keep an eye on the distance between these two, as the night unfolds. The Earth's shadow, too, has moved.
The entire constellation of Leo can now be made out. Orion is now in the west, leaning sideways a bit as if taking a rest. Mars skims the treetops in the north-west. Southward, Crux is high up, with the two Pointers now just about vertical. Achernar, on the other hand, is low down in the south-west. To the east, Scorpius is rising but it's still a bit early to see most of it's stars.
Throughout the morning, three brilliant planets rise (see table for details). First to rise is Jupiter, which shines brighter than the brightest stars. Later, Venus rises, outshining the giant planet substantially. Finally, dimmer Mercury rises in the dawn sky. If you've been observing since midnight, you would now have seen all five naked-eye planets in our solar system.
This is a good time to turn your telescope on Saturn; just after 01:00 it sits as high up as it will get. The closer a star or planet is to the horizon, the more our atmosphere degrades the view, so try and observe objects when they are at their highest. Saturn's well-known rings can just-just be glimpsed in binoculars, but really need a telescope to be appreciated.
Saturn and its moons
Two of Saturn's moons can be seen quite easily in a small telescope. The finder chart will help you identify them, showing their position on Thursday morning at 01:00. Titan lies about 3 Saturn-diameters away and is the brightest (and also largest) moon. Rhea is a bit fainter and much closer. These moons change their positions quite slowly, so the diagram will be pretty accurate throughout the night. Early evening, the moon Tethys is visible just south-west of Saturn; around 01:00 it slips behind Saturn's disc – yet another occultation under way!
From around 02:00, you'll notice that Regulus is closer to the Moon than it was earlier. The Earth's shadow, too, is moving in. Not long now...
(Seen from Cape Town, at 02:00, Regulus is 13' from the lunar edge. But seen from Durban, the two are 23' apart. Seen from most of South America, however, the Moon will occult Regulus – moments before it is itself occulted by our Earth's shadow. More occultations afoot!)
Focus on: the Moon
At 02:34, the Moon moves into the penumbra, which is the region of partial shadow cast by the Earth. Don't expect to see anything happen, though – the Moon will get only very very slightly dimmer. This is perhaps a good time to examine the more prominent features on the Moon.
Prominent lunar features
The diagram identifies a few prominent lunar features. Lighter-coloured regions are rough highland areas, and the dark patches are lower-lying less rugged plains. These dark areas were, in the 17th century, thought to be seas, and the Latin word 'mare' (meaning "sea", pronounced "ma-ray") has stuck. So, for example, Mare Serenitatis, or "Sea of Serenity", is a prominent lunar feature. Many impact craters are visible on the Moon, of which the easiest to see include Tycho, Kepler, Copernicus and Plato.
By this time, the beautiful constellation Scorpius has risen and is arrayed along the eastern horizon. Take a moment to trace the graceful curve of the little critter's back and arched tail, ending in the bright sting. Binoculars will reveal a host of star clusters and nebulae in and around the Scorpion.
03:43
The Moon is now getting lower in the west. Make sure your alarm is set for 03:43 – or better still, 10 minutes earlier. Keep a vigil on the Moon's upper-right edge (Regulus will be near the bottom-right edge), using binoculars, a telescope, or the naked eye. Here, the first signs of the Earth's shadow will manifest – yell out loudly when you see it! As the Moon enters the darkest part of the Earth's shadow, it takes on a reddish colour.
At about 04:00, the crater Copernicus should be bathed in red. By 04:20, half the Moon is under shadow. Ten minutes later, the crater Tycho will be under. A few minutes after that, red colour starts licking at the edges of Mare Crisium. At 04:45, crater Langrenus, near the far edge of the Moon, goes under.
And by 05:00, the entire Full Moon will be bathed in orangey-reddish-coppery light, hanging low above the western horizon.
Epic stuff.
From most parts of the country, the sky will have begun to brighten with the approach of the Sun. From all over southern Africa, the Moon sets, shrouded in our planet's shadow, as the new day breaks.
My advice: pull an all-nighter. Pack a picnic basket and go somewhere neat on Wednesday evening, and watch the Moon and stars do their thing. Yell when you see the Earth's shadow touch the Moon. Take photographs. Chill. Or dance, as the mood takes you – under a red Moon in the pre-dawn sky.
Bloemfontein table of events
| Date | Time | Event |
| Feb 20 (Wed eve) | 18:37 | Moon rises |
| Feb 20 | 19:00 | Sun sets |
| Feb 20 | 19:51 | Sky begins to darken (Nautical Twilight) |
| Feb 20 | 20:20 | Sky completely dark (Astronomical Twilight) |
| Feb 21 (Thur morn) | 02:18 | Jupiter rises (mag –2.0) |
| Feb 21 | 02:35 | Moon enters outer shadow |
| Feb 21 | 03:43 | Moon enters inner shadow |
| Feb 21 | 03:53 | Venus rises (mag –3.9) |
| Feb 21 | 04:15 | Mercury rises (mag 0.6) |
| Feb 21 | 04:20 | Half of the Moon in eclipse |
| Feb 21 | 04:38 | True darkness ends (Astronomical Twilight) |
| Feb 21 | 05:00 | Moon completely within inner shadow (altitude: 12°) |
| Feb 21 | 05:07 | Sky begins to brighten (Nautical Twilight) |
| Feb 21 | 05:13 | Bright satellite: International Space Station (mag –0.3, southeast) |
| Feb 21 | 05:51 | Moon begins to emerge from inner shadow |
| Feb 21 | 06:03 | Sun rises |
| Feb 21 | 06:05 | Moon sets |
| Feb 21 | 07:09 | Moon completely out of inner shadow |
Cape Town table of events
| Date | Time | Event |
| Feb 20 (Wed eve) | 19:16 | Moon rises |
| Feb 20 | 19:37 | Sun sets |
| Feb 20 | 20:00 | Sky begins to darken (Nautical Twilight) |
| Feb 20 | 21:00 | Sky completely dark (Astronomical Twilight) |
| Feb 20 | 21:06 | Bright satellite: Iridium 59 flare (mag –1, low in the South) |
| Feb 21 (Thur morn) | 02:35 | Moon enters outer shadow |
| Feb 21 | 02:37 | Jupiter rises (mag –2.0) |
| Feb 21 | 03:43 | Moon enters inner shadow |
| Feb 21 | 04:13 | Venus rises (mag –3.9) |
| Feb 21 | 04:20 | Half of the Moon in eclipse |
| Feb 21 | 04:38 | Mercury rises (mag 0.6) |
| Feb 21 | 04:42 | Bright satellite: Iridium 72 flare (mag –1, west-northwest) |
| Feb 21 | 05:00 | Moon completely within inner shadow (altitude: 16°) |
| Feb 21 | 05:00 | True darkness ends (Astronomical Twilight) |
| Feb 21 | 05:11 | Bright satellite: International Space Station (mag –0.2, southeast) |
| Feb 21 | 05:30 | Sky begins to brighten (Nautical Twilight) |
| Feb 21 | 05:51 | Moon begins to emerge from inner shadow |
| Feb 21 | 06:27 | Sun rises |
| Feb 21 | 06:32 | Moon sets |
| Feb 21 | 07:09 | Moon completely out of inner shadow |
Durban table of events
| Date | Time | Event |
| Feb 20 (Wed eve) | 18:39 | Sun sets |
| Feb 20 | 18:51 | Moon rises |
| Feb 20 | 19:33 | Sky begins to darken (Nautical Twilight) |
| Feb 20 | 20:03 | Sky completely dark (Astronomical Twilight) |
| Feb 21 (Thur morn) | 01:57 | Jupiter rises (mag –2.0) |
| Feb 21 | 02:35 | Moon enters outer shadow |
| Feb 21 | 03:32 | Venus rises (mag –3.9) |
| Feb 21 | 03:43 | Moon enters inner shadow |
| Feb 21 | 03:55 | Mercury rises (mag 0.6) |
| Feb 21 | 04:17 | True darkness ends (Astronomical Twilight) |
| Feb 21 | 04:20 | Half of the Moon in eclipse |
| Feb 21 | 04:47 | Sky begins to brighten (Nautical Twilight) |
| Feb 21 | 05:00 | Moon completely within inner shadow (altitude: 8°) |
| Feb 21 | 05:13 | Bright satellite: International Space Station (mag –1.9, southeast) |
| Feb 21 | 05:41 | Sun rises |
| Feb 21 | 05:44 | Moon sets |
| Feb 21 | 05:51 | Moon begins to emerge from inner shadow |
| Feb 21 | 07:09 | Moon completely out of inner shadow |
Johannesburg table of events
| Date | Time | Event |
| Feb 20 (Wed eve) | 18:27 | Moon rises |
| Feb 20 | 18:47 | Sun sets |
| Feb 20 | 19:39 | Sky begins to darken (Nautical Twilight) |
| Feb 20 | 20:07 | Sky completely dark (Astronomical Twilight) |
| Feb 21 (Thur morn) | 02:17 | Jupiter rises (mag –2.0) |
| Feb 21 | 02:35 | Moon enters outer shadow |
| Feb 21 | 03:43 | Moon enters inner shadow |
| Feb 21 | 03:51 | Venus rises (mag –3.9) |
| Feb 21 | 04:13 | Mercury rises (mag 0.6) |
| Feb 21 | 04:20 | Half of the Moon in eclipse |
| Feb 21 | 04:36 | True darkness ends (Astronomical Twilight) |
| Feb 21 | 05:00 | Moon completely within inner shadow (altitude: 12°) |
| Feb 21 | 05:04 | Sky begins to brighten (Nautical Twilight) |
| Feb 21 | 05:14 | Bright satellite: International Space Station (mag 0.1, southeast) |
| Feb 21 | 05:51 | Moon begins to emerge from inner shadow |
| Feb 21 | 05:56 | Sun rises |
| Feb 21 | 06:01 | Moon sets |
| Feb 21 | 07:09 | Moon completely out of inner shadow |
Pretoria table of events
| Date | Time | Event |
| Feb 20 (Wed eve) | 18:39 | Moon rises |
| Feb 20 | 18:59 | Sun sets |
| Feb 20 | 19:51 | Sky begins to darken (Nautical Twilight) |
| Feb 20 | 20:21 | Sky completely dark (Astronomical Twilight) |
| Feb 21 (Thur morn) | 02:22 | Jupiter rises (mag –2.0) |
| Feb 21 | 02:35 | Moon enters outer shadow |
| Feb 21 | 03:43 | Moon enters inner shadow |
| Feb 21 | 03:56 | Venus rises (mag –3.9) |
| Feb 21 | 04:19 | Mercury rises (mag 0.6) |
| Feb 21 | 04:20 | Half of the Moon in eclipse |
| Feb 21 | 04:41 | True darkness ends (Astronomical Twilight) |
| Feb 21 | 05:00 | Moon completely within inner shadow (altitude: 13°) |
| Feb 21 | 05:11 | Sky begins to brighten (Nautical Twilight) |
| Feb 21 | 05:14 | Bright satellite: International Space Station (mag 0.2, southeast) |
| Feb 21 | 05:51 | Moon begins to emerge from inner shadow |
| Feb 21 | 06:03 | Sun rises |
| Feb 21 | 06:08 | Moon sets |
| Feb 21 | 07:09 | Moon completely out of inner shadow |
Windhoek table of events
| Date | Time | Event |
| Feb 20 (Wed eve) | 19:08 | Moon rises |
| Feb 20 | 19:28 | Sun sets |
| Feb 20 | 20:18 | Sky begins to darken (Nautical Twilight) |
| Feb 20 | 20:45 | Sky completely dark (Astronomical Twilight) |
| Feb 21 (Thur morn) | 02:35 | Moon enters outer shadow |
| Feb 21 | 03:09 | Jupiter rises (mag –2.0) |
| Feb 21 | 03:43 | Moon enters inner shadow |
| Feb 21 | 04:20 | Half of the Moon in eclipse |
| Feb 21 | 04:41 | Venus rises (mag –3.9) |
| Feb 21 | 05:00 | Moon completely within inner shadow (altitude: 23°) |
| Feb 21 | 05:02 | Mercury rises (mag 0.6) |
| Feb 21 | 05:26 | True darkness ends (Astronomical Twilight) |
| Feb 21 | 05:51 | Moon begins to emerge from inner shadow |
| Feb 21 | 05:54 | Sky begins to brighten (Nautical Twilight) |
| Feb 21 | 06:44 | Sun rises |
| Feb 21 | 06:50 | Moon sets |
| Feb 21 | 07:09 | Moon completely out of inner shadow |
From Sutherland, two Iridium flares occur; at 20:56 (Iridium 58, mag –1, South) and a whopper at 04:34 (Iridium 21 mag –8, northwest). At 05:11 the International Space Station (mag –0.1) is visible in the southeast.
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Keywords: Astronomy, South Africa, total lunar eclipse, total eclipse of the Moon, February 21, digital camera, photographing the eclipse, eclipse photography, digicam
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