Lunar Halo

Something special

A lunar halo, imaged with my Canon 60D camera at 12.26 am on 7th May 2020.

Exposure was 10 seconds at ISO 250.

Imaging a halo is problematic, given the faintness of the halo compared to the bright Moon. In this case a full Moon with considerable high level reflective cloud.

Halos are caused by moonlight refracting through ice crystals in the upper atmosphere. The most common type is the 22° halo (but there is also a 46° halo, although this seems to apply mostly to the Sun).

This image of a 22° halo was taken with my Tamron 10-24 mm lens at about 13 mm focal length. The nominal vertical of this lens at 13 mm is about 70° and this ring appears to cover about 70% of the vertical.

A rough calculation indicates it has a diameter of about 49° and a radius of 24.5° – slightly larger than 22° but close enough to confirm that it is really a 22° Halo.


Nothing special

Listen up, everyone.

Shortly afterwards, I took this image of the Full Moon with a 200 mm focal length, before finishing the session:

Full Moon near perigee. Diameter 33.7 arc-min
7th May 2020

Full Moon near perigee. Apparent diameter 33.7 arc-min
Canon 60D, 200mm lens, 1/3000th sec, ISO 1250, f/4
7th May 2020

At this time the Moon was a few hours past perigee and just a few more hours short of full Moon.

It’s a Super Moon? Noooooooooooo!

It’s nothing special and it’s certainly not “super”. It really disappoints me when even some astronomers adopt a silly non-astronomical hyped up name which originated from astrology and is propagated ad nauseum by the mass media.

There is nothing special about this Moon as far as astronomers are concerned and if you really want to get the name right, it’s a “perigee syzygy” (of the Earth–Moon–Sun system) – or better still, just call it “a full Moon near perigee“.

Now repeat after me: “It’s nothing special. It’s not super. It’s just a full Moon near perigee“.

Say it again.

Louder.


2018-03-10 Telescope & Roger
Images © Roger Powell
I’m one of the founding members of Macarthur Astronomical Society,
Australia. 🙃

3 Comments

  1. Not a ‘supermoon’, but I wish I had noted the closeness to perigee in my monthly write-ups, since we’ve had coastal flood warnings the last few days here on the east coast of the USA. Closer in March and April. Warnings at >https://www.weather.gov/< Unrelated, but we are forecast to set record low temperatures for this day in May tomorrow over much of the eastern USA. Sand some snow flakes may make it to the coast.

    Liked by 1 person

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