After all the excitement surrounding the Great American Eclipse earlier this year, it is easy to forget that another one of these mesmerising events was scheduled for the fall. This second eclipse of the year was an annular one (as observed from ground), which is even more rare than a regular (partial) eclipse. During an annular eclipse, the Moon is further from Earth in its orbit and thus appears smaller than during a total solar eclipse. As a result it can not cover the complete solar disk. We observe a ring (an annulus) of bright sunlight surrounding the Moon.
The October 2 annular eclipse was difficult to observe from ground. Its shadow passed over the very tip of South America, so only observers in Chile and Argentina were able to enjoy this spectacle. Larger parts of South America and even New Zealand could observe a partial eclipse with various degrees of occultation.
PROBA2, on the other hand, again profited from its fast sun-sunchronous orbit to observe the event multiple times. The Moon passed 5 times in the field-of-view of the SWAP instrument, of which 3 transits obscured at least part of the solar disk. Two covered a significant part of the solar disk, obscuring up to 75% and 62% of the solar surface. Click on the image below to see the movie of the observations of the eclipse from the SWAP telescope.
As for all eclipses, LYRA activated one of its backup units, which acquires in parallel with the nominal unit. The instrument monitors the progressive extinction of the solar light in its channels that we observe in the ultraviolet (red and green curves) and extreme ultraviolet (black and blue curves). The signal extinction caused by the Moon passing in front of the Sun, as observed across the four channels of the backup unit, is presented below. During the second passage, this extinction occurred while the Sun was recovering from an eruption, which explains the overall decrease in signal observed before and after the eclipse in two of the LYRA channels (blue and black).
All observations and movies can be found in this directory: https://proba2.sidc.be/Events/2024-Oct-02-SolarEclipse/ .
