An observer in or near the path of totality for the April 8 solar eclipse can make useful observations of the appearance of the moon's shadow projected onto the moon. the Earth's atmosphere, before, during and after mid-eclipse. Sky darkness studies can also be valuable.
At the time of a total solar eclipse, the moon's shadow cone intersects the ground into an ellipse, with the major (long) axis pointing toward the sun. Because the shadow moves quickly, its appearance is constantly changing. Careful descriptions of the moment-by-moment sky near totality can be important, especially observations of the moon's shadow seen against the sky as it approaches just before totality and recedes just after.
For the upcoming solar eclipse, a prominent shadow should appear a few minutes before the onset of totality, mimicking an approaching storm and moving from the west-southwest sky toward the observer.
Related: How to give yourself the best chance of clear skies during the April 8 solar eclipseYou can watch the total solar eclipse live here on Space.com. And stay up to date on all the action with our total solar eclipse 2024 live updates blog.
Exotic colors and lighting
I've often been asked: Why should I bother traveling to an eclipse? My answer is always the same: "You have to see one for yourself, and then you will understand." Astronomy writer Guy Ottewell planned to make a painting of the 1983 solar eclipse, visible from Borobudur in Java. He later wrote in his book: ' The understanding of eclipses:
"During the minutes of totality, I was aware that I was in another visual world; that I was trying to remember colors for which I had no name, which would be as difficult to remember or describe as a taste."
For those who witness the total phase, the moon's shadow above the head appears dusky blue (if there is none). clouds), and the light from outside the edge forms a bright edge around the horizon. The saffron hue of the sky outside the shadow of an eclipse can be especially impressive. Because air scatters long wavelengths of light, less than short ones, light from outside the shadow is yellowed or colored red; the exact color depends on the distance from the shadow edge to the observer. At 50 miles or more the bright red glow is pronounced and the bright tan glow is low. Because one may be as much as 50 to 60 miles from the edge of the shadow at the upcoming eclipse - if positioned on the centerline of the eclipse path - some vibrant colors may be visible, especially toward the northwest and southeast at mid-totality.
An outside view on the path of totality
Related stories:
- What happens if it's cloudy during the April 8 solar eclipse?
- How long will the April total solar eclipse last?
- Why you don't need to go to the center line for April's total solar eclipse - and what will happen on the edge
Outside the path of totality, even at a considerable distance, one can sometimes project the moon's shadow against the atmosphere. In the solar eclipse of July 9, 1945, the shadow was seen near the horizon from Portland, Oregon, 320 miles (515 km) west of the point where the solar eclipse was first total at sunrise. Also during the solar eclipse of October 2, 1959, which occurred totally over eastern Massachusetts, the shadow was visible on the northeastern horizon to an observer just 15 miles northeast of New York City. The closer the distance from the path of totality, the greater the chance of seeing the shadow.
There are several methods to observe the degree of darkness during the lunar eclipse. One way is to write down the smallest size of newsprint that is readable. This can be done even when the sky is cloudy, but the type and extent of cloud cover must be carefully recorded. Also useful and even better than visual techniques are good photographs of the entire sky (using a fish-eye lens or convex wide-angle mirrors), or photometric measurements with photoelectric meters.
A second way is to note the faintest visible star or planet.
Cameo appearance by stars and planets
When the sun is completely darkened, the sky does not appear (as many astronomy guides suggest) "as dark as a moonlit night". Instead, it gets dark about 20 to 40 minutes before sunrise or 20 to 40 minutes after sunset. In such a sky, Venus is usually very conspicuous, and other bright planets and first-magnitude stars have also been reported near the Sun.
Venus will be by far the brightest object optically size -3.9. On the day of the eclipse it will be about 15 degrees west (lower right) of the sun. So your clenched fist, held at arm's length, measures about 10 degrees Venus will be about "a fist and a half" from the sun. Jupiter at magnitude -2.0, second in brightness to Venus, it will lie 30 degrees east (upper left) of the Sun.
There will be other planets nearby, but the question is whether they will be easily visible. Saturn (size +1.1) and Mars (magnitude +1.2) will be 35 and 36 degrees west of the Sun respectively. Small Mercury will be half a dozen degrees east of the Sun, but at a very faint magnitude +4.3, so it will be invisible.
As for the stars, this eclipse will give you a great opportunity to gauge the brightness of the sky, as the bright stars of the winter season will be well placed across much of the eastern part of the sky. It is low towards the east-southeast Sirius, the brightest of all stars at magnitude -1.5. However, if you are along the path of totality in Texas or Mexico, you will not see it because it is below the horizon. Capella (magnitude +0.1) will be high in the east-northeast, while Rigel (magnitude +0.2) will be much lower in the southeast. A few fainter first magnitude stars may appear here and there, but the light from the corona and the general scattering of light filtering in from outside the umbra will extinguish most stars.
But maybe spending all your time picking out stars and planets isn't the best choice. A known lover of stars and star signs was George Lovi (1939-1993), who wrote the popular column "Rambling Through the Skies" in Sky & Telescope magazine for more than twenty years. Mr. Lovi often explained the beauty of the completely eclipsed sun as seen through binoculars or even through the telephoto lens of a camera. "The human eye," he wrote, "has an unparalleled ability to perceive subtle details within the inner and outer corona in a way that no emulsion can."
But then he also took issue with those who engaged in what he called the "sometimes ridiculous attempts" to locate stars and planets during the total phase of the eclipse. "Some devotees spend virtually all those precious minutes searching!" he ranted, adding, "I can't possibly imagine how this relates to the main event!"
I agree with Mr. Lovi on that point (I have traveled to 13 total solar eclipses myself); you would probably be better off spending much of your valuable time concentrating on viewing the solar corona.
As someone said to me later, after spending all his time trying to photograph a total solar eclipse to no avail:
"I therefore came to the conclusion, and it represents a piece of wisdom, obtained at great expense and hardship, which I feel compelled to pass on to other enthusiasts, and that is to say: the best possible way to see a solar eclipse is simply LOOK AT IT!"
This is perhaps the best advice for anyone planning to observe the spectacle of a total solar eclipse. So remember, if you get the chance to buy one, just LOOK at it and ENJOY.
After all, even in 2024, a few minutes of wonder is all you get!
To view this entire event safely, you must use sunscreens. Only those on the path of totality will be able to briefly remove them to see the Sun's corona with their naked eyes. Those who are not on the path of totality should keep them all the time.
Anyone observing the partial phases of this eclipse - and for those outside the path of totality, that is the entire event - will need to wear eclipse glasses, while cameras, telescopes and binoculars will require solar filters for their lenses.
Us how to look at the sun safely guide tells you everything you need to know about safe solar observations.
