Solar Eclipse: Are you ready for another total ? After the great American eclipse of August 2017, another spectacular show is set to happen in July of this year! Here’s all you need to know about it!
On July 2nd, 2019, a total solar eclipse will happen again in the southern hemisphere. Most of the eclipse (whether total or not) will project a shadow over the Pacific Ocean. Totality will be visible from some island there (Oeno island for example) and the greatest eclipse will be there (maximum of 4:33 minutes of totality). If you are in Chile and Argentina, where the path of totality will also end, you will benefit from about 2:30 minutes of totality, should atmospheric conditions align.
Credits: Michael Zeiler
A solar eclipse occurs when an observer on Earth passes through the shadow cast by the Moon, which fully or partially blocks (“occults”) the Sun. This can only happen when the Sun, Moon and Earth are nearly aligned on a straight line in three dimensions during a new moon when the Moon is close to the ecliptic plane. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses, only part of the Sun is obscured.
If the Moon were in a perfectly circular orbit, a little closer to the Earth, and in the same orbital plane, there would be total solar eclipses every new moon. However, since the Moon’s orbit is tilted at more than 5 degrees to the Earth’s orbit around the Sun, its shadow usually misses Earth. A solar eclipse can only occur when the moon is close enough to the ecliptic plane during a new moon. Special conditions must occur for the two events to coincide because the Moon’s orbit crosses the ecliptic at its orbital nodes twice every draconic month (27.212220 days) while a new moon occurs one every synodic month (29.530587981 days). Solar (and lunar) eclipses therefore happen only during eclipse seasons resulting in at least two, and up to five, solar eclipses each year; no more than two of which can be total eclipses.
2017 total solar eclipse in Salem, Oregon, USA
Total eclipses are rare because the timing of the new moon within the eclipse season needs to be more exact for an alignment between the observer (on Earth) and the centers of the Sun and Moon. In addition, the elliptical orbit of the Moon often takes it far enough away from Earth that its apparent size is not large enough to block the Sun entirely. Total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth’s surface traced by the Moon’s full shadow or umbra.
Chile offers some very good atmospheric conditions for the eclipse, especially if you drive up in the Andean mountains. The weather west (Chilean coast) and east of the Andes in Argentina is a bit more uncertain because of clouds at this time of year. In both countries, the eclipse will be visible in the afternoon. In eastern Chile around La Silla telescope (near La Serena), totality will start at 16:39:23 LT and end at 16:41:15 LT. At the center of the totality path, you will have up to 2:33 minutes! In both Chile and Argentina, the eclipse will be quite low in the sky. The Sun will be setting and this can both give advantages and drawbacks.
One of the advantages is that you will be able to take wide-field pictures, including a foreground. If you are shooting in the Andes, you will probably get a nice arid foreground as well. Bright Venus will also potentially be in your shot provided you are shooting wide enough. However there are also some downsides to this sunset eclipse. Since the sun will be lower in the sky, the atmosphere might have a greater negative effect on your optics: deformation, bending, color-shifting… If you have a partially cloudy sky as well, the eclipsed sunlight will have to potentially cross more clouds to get to you. One more reason to try and get away from the valleys and coast! A good estimate about the weather patterns for the season says that in the mountains, the sky has 30% chance of beingcloud-free, 55% chance of being partially clouds and 30% chance of being completely overcast.
Our resident astrophotographer Adrien Mauduit will travel to Chile to hopefully bring back gorgeous pictures of the event. We will keep you posted!