We humans of planet Earth benefit from a great coincidence. It's a coincidence of time, and of space and of maths. The coincidence is this: the sun is about 400 times wider than the moon and it's also an average of about 400 times farther away from the moon.
The apparent size of the object in the sky depends upon how far the object is and how big it is. So these numbers being equal means Sun and the Moon means to be about the same size in the sky and that's where another interesting thing comes in: Sometimes the moon passes directly between the Earth and the sun. It doesn't happen all that often, but when it does, we get magic, We get an Eclipse.
An eclipse is a generic term in astronomy for "when one object passes into the shadow of another object, darkening or blocking it.
A solar eclipse happens when the Moon blocks the Sun, casting a shadow on the Earth.
A lunar eclipse happens when the Earth blocks the Sun, casting a shadow on the Moon.
The Moon orbits the Earth once per month, and the Earth orbits the Sun once per year. If the Moon's orbit were perfectly aligned with the Earth's essentially sharing the same plane, we'd get a solar eclipse on every new moon, and a Lunar eclipse on every Full moon! But we don't because the moon's orbit is tilted with respect to Earth's about 5 degrees.
It means that, at the new moon, the moon can be as much as 5 degrees away from the sun, passing above or below the sun in the sky, thereby missing it from our perspective.
But sometimes the moon is at the right place and at right time, and a new moon, it lies perfectly in line between the sun and the Earth. and we get a Solar Eclipse.
What happens in space is moon is casting a long shadow. Usually, that shadow misses the Earth but during an Eclipse the moon's shadow falls on the Earth surface. In fact, there are two shadows from the sun one inside the other.
One is a narrow cone, tapering to a point away from the moon. If we're anyway inside this cone, the moon appears big enough to completely blocks the Sun. That means that shadow is very dark and we call it the Umbra (which is a Latin word means shadow ). Outside of this deep umbral shadow is a wider conical region where, if you're in it the sun is partially blocked.
You can see some of them passed the moon. You're getting less light and you're technically shadowed, but it's not quite as dark as Umbra. This region is called the Penumbra ( pen means almost or nearly ).
When the umbra touches the Earth, we get a total Solar Eclipse.
When the solar eclipse happens, you might think that this means the sky get dark, and it's like right outside for a while. But a total eclipse is for more than that and that's because of the sun's corona (The corona is the sun's atmosphere). An ethercally thin envelope of gas that streches from the sun's surface into space of million's of kilometer's.
When the moon blocks the sun's face the corona becomes visible. It surrounds the sun, filament and tendrils extending into the sky, an incredible beautiful sight.
The moon's edge isn't smooth - there are crators and other depression. Crators right at the moon edge allow sunlight to stream past.
We see them as bright patches around the eclipses sun, which are called Bailey's Beads. They are first described by English Astronomer Bailey in 1836!.
When totality starts , it takes 7 or 8 minutes the umbra to move from one spot on the earth's to move off the Sun's for a moment just a single spot of the sun is unblocked glowing fiercely on one side of the moon.
Sometimes, we get a circle of light around the moon surface and together with bright spot. This is called the diamond ring.
The Moon's orbit around the Earth is an ellipse. This means it closes to the Earth and sometimes farther away.
If a solar eclipse happens when the moon is at the far end of its orbit, it can actually be smaller than the sun is the sky. It doesn't block the entire face of the sun, and it leaves a ring of lighr around the black circle of the Moon.
The Techincal name of this shape is "Annulus". This event is called an Annular eclipse.
A solar eclipse is localized to one spot on the Earth or really a swoth the ground as the moon's umbral shadow sweeps across the Earth's surface.
But a lunar eclipse is when the moon moves into shadow, so anyone on Earth facing the Moon can see a Lunar eclipse.
The Earth has umbral and Penumbral shadows, too . When the moon first enters the Earth's penumbra the dimming is so slight, we can hardly notice it. But as the moon moves deeper into Penumbra, it starts to darken.
The Earth is bigger than the moon so Earth's Penumbra is much wider, while a solar eclipse is over in minuters, Total lunar eclipse can last 2 min.
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