Moon eclipse, 21-Jan-2019, from ESAC.

CESAR team witnessed and recorded, on 21st January 2019, a lunar eclipse from its location at ESAC (European Space Astronomy Center). We composed this timelapse with 100 of those images. A moon eclipse happens when the moon passes into Earth's shadow (What is an eclipse?). Unlike with solar eclipses, you need no special equipment to observe lunar eclipses. You can safely view the eclipse directly with the naked eye. 

The eclipse started at 03:36 local time with the usual penumbral part. At 04:34 the dark umbra touched the moons'disk. The moon went into total umbral eclipse at 05:41, for 62min duration until 06:43 CEST. At 07:50 the total eclipse ended. The Moon completely left the Earth's shadow penumbra at 08:48, when the Sun was already rising. 

In the next composite image you can have a feeling of the actual extent of Earth's shadow, and the actual path that the Moon took through it.

• The Earth's shadow is artistically composed by rotating 7 partial eclipse images to complete the shadow circle. This is not a real shadow view, but provides a nice feeling of how big the Earth's umbra is, compared to the Moon diameter. It also helps as a background for placing the umbral images. Earth's umbral shadow is about 2.6 times the diameter of the Moon.
• The Moon's actual path is realistically represented, though, in the umbral part. The 3 reddish images are taken with longer exposures, at the start, middle and end of total umbral eclipse. These are then placed over the artistic shadow background. Time increases from right to left, as the moon travels through the shadow. Note that the last partial image on top right is as well correctly placed.
• The path of the Moon in this 21-Jan-2019 eclipse was not central, and that is why the red moon had a bright whitish limb. This bright zone rotated around the limb in the 1h umbral time, following the closest point to the umbral circle. The grading of colors is very different to the more central eclipse that ocurred on Jul 2018.

Composite image showing the Earth's shadow extent and the total eclipse path (video here).

Star occultations during the Moon eclipse, 21-Jan-2019, from ESAC. Left: ingress at 4:56 UTC, HIP 39869 Cnc (video ingress). Right: egress at 05:21 UTC, HIP 39749 Cnc (video_egress).

Eclipse timelapse.

But the Moon does not go fully black during eclipse. It turns deep red because some of the sunlight passing Earth's atmosphere is refracted around our planet's limb and hits the moon's surface. Earth's air also scatters more shorter-wavelength light (in colors such as green or blue); what's left is the longer-wavelength, redder end of the spectrum. It is the same phenomena responsible for sunrises and sunsets: actually the Moon's blood color comes from all the sunrises and sunsets taking place at the same time around the world along the terminator line (day-night boundary).

The eclipse as seen from ESAC (images Manuel Castillo). Canon EOS550D. Telescope CG8 20 cm aperture.

For the event, the CESAR team set up several cameras and telescopes:

- 1 newtonian telescope CG8 20 cm aperture with a Canon EOS550D camera

- the white visible Solar dome telescope (9cm aperture) was used with a Sony alpha 7 sII camera for livestream

If you want to know how to take images during a lunar eclipse, please look at this video produced with the CESAR equipment, and explained by CESAR personnel. 

The event streaming was recorded live in a experimental set-up.

You can re-watch the event in our youtube channel.

The event was followed by ESA_comms and ESAC-Spain comms (thanks Arantxa Alonso @ ESAC, Emily Baldwin and Claudia MIgnone @ ESTEC). CESAR worked on several news around the event :

• The ins and outs of a lunar eclipse - ESA main portal news
• What is an eclipse? - ESA comms infographics
• How to photograph a lunar eclipse? - ESA comms with CESAR equipment and personnel explanations

The CESAR observing team, with some ESAC astronomy club members. Note the eclipsed moon at the top right)