For those of us fortunate to be able to see this, don’t miss it, it will be the best opportunity this century.
Red alert for stargazers as moon and Mars put on show of a lifetime
July 23 2018, 12:01am,
When a blood moon combined with a lunar eclipse in September 2015 it drew crowds to Glastonbury Tor in Somerset
One of the most spectacular sights in the night sky will begin at sunset on Friday when the longest blood moon of this century combines with Mars in opposition.
The unusual alignment will have astronomers and amateur stargazers alike looking to the heavens for a show unlikely to be matched for many years.
The main event is the 21st century’s longest lunar eclipse, an event that happens when the Moon passes through the Earth’s shadow.
Astronomers have been unusually lyrical in describing what they will see. “It is a beautiful sight and one that reminds us we have souls; to take a moment to look at the sky,” Robert Massey, deputy director of the Royal Astronomical Society, said.
The blood moon is so named because of the reddish hue it takes on. Rather than the Earth entirely blocking sunlight reaching the moon, the light is refracted. Depending on the amount of moisture and dust in the Earth’s atmosphere — affected by disturbances such as volcanoes — the effect is to scatter light and make the moon appear red. This could be anything from salmon pink to a dark red hue.
The total eclipse will last about one hour and 43 minutes, longer than normal partly because the moon is at its farthest from the Earth. Its orbit is a little slower than usual because the distance makes the gravitational pull weaker. The moon therefore stays in the Earth’s shadow for longer. It will look smaller than usual because it is so far away.
In addition the alignment of the moon means that it will be passing the centre of the Earth’s shadow. Eclipses are shorter when the moon passes north or south of the shadow’s centre.
The entire spectacle of the moon being affected by the shadow will last for about six hours.
Also on Friday, Mars will move into opposition, meaning that it and the sun will be on directly opposite sides of Earth, making it appear redder than usual. From our perspective, Mars rises in the east just as the sun sets in the west, and then sets in the west just as the sun rises in the east.
The lunar eclipse will be seen best from the Indian Ocean, Madagascar and the Middle East. The moon is due to rise at 8.50pm in Greenwich, meaning that astronomers in Britain will miss the start of the eclipse.
The maximum eclipse will be at 9.21pm. The total eclipse will end at 10.13pm. When the partial eclipse ends at 11.19pm, the moon will lose its red colour. The penumbral eclipse, when the moon is in the outer shadow of the Earth, ends at 12.28am. Mars should be at its brightest at 1.15am.
The events can be seen looking southeast with the naked eye, but binoculars or a telescope will offer a clearer view. Viewers should find a clear horizon, away from hills or tall buildings.
Christopher Columbus is said to have taken advantage of a blood moon in 1504 when he found himself stranded in Jamaica in need of provisions, with the locals reluctant to help. Adept at astronomy, he told tribal leaders that his god would turn the moon blood red if they failed to help him. When that happened on cue, they were overawed and brought food.
The Royal Observatory Greenwich will be streaming the lunar eclipse live on Facebook, using its new Annie Maunder astrographic telescope.
Astronomical societies all over the country are gathering to look upwards in unison. In Cornwall the Friends of Par Beach together with Roseland Observatory are having a family evening out at a picnic area near St Austell.
Exactly what they will be able to see depends on the weather, and not only on conditions in Britain. Tom Kerss, an astronomer at the Royal Observatory Greenwich, noted that conditions farther afield would affect visibility. “Mars is engulfed in a dust storm,” he said. “It is essentially featureless while the dust cloud is covering the planet.”
If that clears, viewers with binoculars might be able to pick out features such as the planet’s volcanic plains.
The Met Office suggests that it will be cloudy in the west and northwest but fine elsewhere.
Chris Lintott, of the University of Oxford, said: “Lunar eclipses are beautiful and everyone can enjoy them. Go outside on Friday, look to the horizon, and watch the eclipsed moon rise — it couldn’t be simpler.”