[BAA-ebulletin 01024] EARLY MORNING TOTAL ECLIPSE OF THE MOON THIS MONDAY

[BAA electronic bulletins service]

EARLY MORNING TOTAL ECLIPSE OF THE MOON THIS MONDAY



This coming Monday, in the early morning hours of January 21, there will be
a total eclipse of the Moon.  Full Moon itself occurs at 05:16 UT on January
21 with lunar perigee (its closest approach to the Earth) occurring just 14h
43m later at 19:59 UT. When a Full Moon occurs close to the Moon's perigee,
it is often dubbed a 'Supermoon'.  This is why some people are calling this
is a 'Supemoon eclipse'.

Eclipses of the Moon occur when the Full Moon passes through the cone of
shadow cast by the Earth into space. Weather permitting this will be a
fascinating event to watch from the British Isles because the eclipse will
be visible in its entirety everywhere, giving plenty of opportunities for
stunning pictures of a 'ghostly red Moon'.

 

The lunar eclipse begins at 02:36 UT (in the early hours of Monday morning)
when the Moon enters the fainter outer part of the Earth's shadow known as
the penumbra. At this time the Moon will be fairly high in the south-west,
almost directly below, and in line with, the stars Castor and Pollux in
Gemini, the Twins. 

 

The main phase of the eclipse begins at 03:33 UT when the Moon first enters
the central, dark part of the Earth's shadow known as the umbra and the
partial eclipse begins. The eclipse becomes total at 04:41 UT and lasts for
a full 1 hour 2 minutes. Maximum eclipse is at 05:12 UT.  At this time the
Moon will be dropping down into the western sky, among the faint stars of
Cancer, the Crab, but still high enough to be well clear of trees and
buildings. 

 

The total phase of the eclipse ends at 05:43 UT. As the Moon will be passing
through the upper part of the Earth's umbral shadow, it is probable that the
northern parts of  the eclipsed Moon may appear quite bright even during
mid-totality, but one never quite knows how dark or how bright a lunar
eclipse will be. Everything depends on the conditions in the Earth's upper
atmosphere through which all light falling onto the shadowed Moon has to
pass. There have been lunar eclipses when the Moon has been difficult to
find even with a telescope, while at other eclipses it has remained bright
red or vividly coloured.  The Moon appears a reddish hue because of Rayleigh
scattering - the same effect that causes sunrises and sunsets to appear
reddish - and the refraction of that light by the Earth's atmosphere into
its umbral shadow.

 

The partial eclipse ends at 06:50 UT, when the Moon exits the umbra. By this
time the Moon will be getting quite low in the west-north-western sky. The
faint penumbral phase finally ends at 07:48 UT.

  

And don't forget that if you do get up before dawn to watch the lunar
eclipse that Venus and Jupiter are still a spectacular sight together in the
south-eastern twilight sky, with Venus much the brighter of the pair a few
degrees above Jupiter.

 

Let us hope for clear skies in the early morning hours of Monday, January
21!

 

 

This e-bulletin issued by:

Dr John Mason

Press and Publicity Officer

British Astronomical Association

 

2019 January 18