The Lunar Eclipse that marks the Apollo 50th

A partial lunar eclipse occurring on the 16-17 July 2019 coincides with the 50 years anniversary of Apollo 11 launching to the Moon. What does that mean?

ap11-s69-40640hr.jpg
Apollo 11 launch to the Moon, credit NASA, 16 July 1969

To eclipse means to obscure the light from one celestial body by the passage of another between it and the observer or between it and its source of illumination. Blocking, covering, obscuring, concealing, darkening, occulting are synonyms to eclipsing.

So what’s this eclipse blocking?

This time is the direct light from the Sun shining into what we call a Full Moon. This is a partial eclipse so only a part of the Moon will be blocked.

What’s hiding it?

It’s the Earth. The Earth is in between the Moon and the Sun.

Shouldn’t the Moon be totally dark during a total eclipse then?

Covering the Moon with the shadow of Earth is like you’d try to darken an object by standing between the light source and that object. Some light still gets to it.

Why is the Moon turning red during an eclipse?

Earth blocks direct sunlight from reaching the Moon. But there is some light, that is refracted by Earth’s atmosphere that still gets to the Moon. This is reflected back and is why we still see the features from the Moon. This light appears reddish for the same reason that a sunset or sunrise does: the Rayleigh scattering of bluer light.

When is it?

An eclipse can last anything from a few minutes to hours. They don’t just happen but there is a process. From Wellington, the Moon will set during the eclipse so, providing clear skies, we will only be able to catch a glimpse. The total duration of the eclipse is 5 hours, 34 minutes. The duration of the partial eclipse is 2 hours, 58 minutes.

Event UTC Time Time in Wellington* Visible in Wellington
Penumbral Eclipse begins 16 Jul at 18:43:51 17 Jul at 6:43:51 a.m. Yes
Partial Eclipse begins 16 Jul at 20:01:43 17 Jul at 8:01:43 a.m. No, below the horizon
Maximum Eclipse 16 Jul at 21:30:44 17 Jul at 9:30:44 a.m. No, below the horizon
Partial Eclipse ends 16 Jul at 22:59:39 17 Jul at 10:59:39 a.m. No, below the horizon
Penumbral Eclipse ends 17 Jul at 00:17:38 17 Jul at 12:17:38 p.m. No, below the horizon

Data from DateandTime.com

* The Moon is below the horizon in Wellington some of the time, so that part of the eclipse is not visible.

Link to the full NASA info sheet: LE2019Jul16P

What to expect?

Expect 240 solar eclipses and 380 lunar eclipses worldwide each century. On a quick look online there are even guides to how to cope with an eclipse and the general idea is that eclipses bring news of big events. Here’s the thing, most years have 4 eclipses, which is the minimum number of eclipses that take place in a year; 2 of these 4 eclipses are always solar eclipses. While rare, the maximum number of eclipses that can take place in a calendar year is 7. That’s a lot of big news.  In a century, even more big news, 380 lunar eclipses and about 240 solar eclipses.

This year it coincides with the 50 years anniversary of the Apollo 11 launch, which is a neat coincidence and a reason to learn more about the Moon and celebrate the extraordinary achievement of stepping on another celestial body, our natural satellite.

More reading

Partial Lunar Eclipse 16-17 July 2019 on timeanddate.com 

Royal Astronomical Society of New Zealand eclipse page

NASA eclipse website

Photopills’ guide to Lunar eclipses

The Last Lunar Eclipse of 2019 Occurs Tuesday, Just in Time for Apollo 11 Celebrations