Local astronomy enthusiast reminisces rare night of lunar eclipse and Mars opposition • “For the two events to take place on the same night, in the same small bit of sky, right over Seychelles, was an amazing event, not to be repeated for thousands of |17 August 2018

A lunar eclipse occurs when the sun, the earth and the moon are exactly or very closely aligned. The direct light from the sun is blocked by the earth and thereby casts a shadow onto the moon.

Lunar eclipses only occur during a full moon and can be observed by anyone on the night side of the planet. During this rare event, the moon takes on a reddish colour which is sometimes referred to as the ‘Blood Moon’.

This phenomenon is as a result of the scattering (or filtering out) of short wavelength (blue) light from the sun in the earth’s atmosphere, thus allowing only the longer wavelength (red/orange) light to reach and illuminate the moon, hence the characteristic red moon appearance.

The shadow cast by the earth is actually made up of two shadows, the penumbra (partial shadow) and the umbra (full shadow); the umbra is nested inside the penumbra. During a total lunar eclipse, the earth’s penumbra first passes over the moon, followed by the inner, full shadow, which is as a result of the earth blocking all sunlight from reaching the moon.

Below, a local astronomy enthusiast with over ten years experience observing the Seychelles’ night sky, gives his account of the recent, long-lasting lunar eclipse that was clearly visible from our islands.

“July 27, 2018 was a ‘Red Letter’ day for Seychelles sky watchers. Firstly the ‘red’ planet Mars reached its brightest for 15 years and won't be so again until 2035. It is still nearly as bright to the East about an hour after sunset, so go and have a look tonight, about 4 fists (20 degrees) up. It is at opposition, namely the sun, Earth, and Mars are in a line in that order. Mars is even more bright than normal because of a planet-wide dust storm, but unfortunately only the polar ice cap can be seen through a telescope as local observers were looking forward to seeing surface details at opposition, possibly the famous-fictitious-canals”.

“Secondly, that night, coincidently there was a ‘red’ moon from the longest and deepest lunar eclipse of this century, as the moon passed right through the middle of the Earth's shadow, and the dust in our atmosphere turned it orange/red for an hour. It took on a 3D effect and looked like a ball about to fall, amazing! Next similar event is in 2123... don't hold your breath!”

“Seychellois observers were also struck by the sight of the full moon overcoming (very) nearby Mars’ brightness, only to be defeated for an hour as Mars flamed during the total eclipse at midnight. I myself got 40 winks at 9pm to be fresh as a daisy at 12! Also noted locally was how similar the eclipsed moon looked to Mars through a telescope. For the two events to take place on the same night, in the same small bit of sky, right over Seychelles, was an amazing event, not to be repeated for thousands of years I suspect. Finally, thank you met office for an amazing clear sky between two very cloudy days, how did you do that?”

References: Mr. Eclipse; Science Alert