5 April 2015
Following on from the impressive solar eclipse in March this year, we have a total lunar eclipse coming up in the early morning of 28 September.
Lunar eclipses are more common than their solar cousins but can, nevertheless, be most impressive. Their mechanism is straightforward: as the Earth orbits the Sun, it casts a sweeping shadow away from the Sun as it moves. A lunar eclipse occurs when the Moon (as part of its own orbit around the Earth) falls into that shadow.
By definition, a visible solar eclipse must occur during daylight; similarly, a visible lunar eclipse must occur at night – this one will reach totality at 3.47am (BST) – so are probably more accessible to dedicated astronomer hobbyists! The event will be equally visible (weather permitting) to all who can see the moon at this time.
What can we expect to see? The picture gives a good idea. In theory, one might expect the moon to be blotted out into darkness by the Earth’s shadow. In reality, the Earth’s atmosphere tends to act as a sort of lens, refracting some of the Sun’s light around and casting a dim red ‘sunset’ effect onto the Moon.
Is it safe to observe? – absolutely! Light intensity is much less than normal and it is completely safe to observe the full moon even through a telescope, so a lunar eclipse presents no problems. Should also be a promising and straightforward candidate for some pictures.
More information on timings and what one should expect to see can be found on the Time And Date website.