The planet Mercury is closer to the Sun than the Earth is, so it can sometimes come between Earth and Sun. That's called a transit. A transit is like a failed solar eclipse: In a solar eclipse, the Moon gets between Earth and Sun and blocks all sunlight. In a transit, Mercury blocks only a small fraction of the Sun's light because Mercury isn't close enough to us to completely block our view of the Sun. We want to calculate by how much the Sun will be dimmed when such a transit occurs, because that's important to know for satellites which are powered by solar panels (shown hovering around the Earth in the image above). Without Mercury in the way, the radiation intensity that hits the top of the Earth's atmosphere from the Sun is 1,360.8 W/m2 (W stands for Watt, measuring energy transferred per second). The fraction of this intensity that is blocked by Mercury during a transit is equal to the ratio between the cross-sectional area of Mercury (as seen from Earth) and the cross-sectional area of the Sun (also as seen from Earth). (a) The ratio between the radii of Mercury and the Sun, as seen from Earth, is 0.006, so the ratio between the cross-section of Mercury and that of the Sun is: _______ (b) The drop in solar power during a transit, in W/m2, is approximately equal to: _______
Stellar evolution
We may see thousands of stars in the dark sky. Our universe consists of billions of stars. Stars may appear tiny to us but they are huge balls of gasses. Sun is a star of average size. Some stars are even a thousand times larger than the sun. The stars do not exist forever they have a certain lifetime. The life span of the sun is about 10 billion years. The star undergoes various changes during its lifetime, this process is called stellar evolution. The structure of the sun-like star is shown below.
Red Shift
It is an astronomical phenomenon. In this phenomenon, increase in wavelength with corresponding decrease in photon energy and frequency of radiation of light. It is the displacement of spectrum of any kind of astronomical object to the longer wavelengths (red) side.
The planet Mercury is closer to the Sun than the Earth is, so it can sometimes come between Earth and Sun. That's called a transit.
A transit is like a failed solar eclipse: In a solar eclipse, the Moon gets between Earth and Sun and blocks all sunlight. In a transit, Mercury blocks only a small fraction of the Sun's light because Mercury isn't close enough to us to completely block our view of the Sun.
We want to calculate by how much the Sun will be dimmed when such a transit occurs, because that's important to know for satellites which are powered by solar panels (shown hovering around the Earth in the image above).
Without Mercury in the way, the
(W stands for Watt, measuring energy transferred per second).
The fraction of this intensity that is blocked by Mercury during a transit is equal to the ratio between the cross-sectional area of Mercury (as seen from Earth) and the cross-sectional area of the Sun (also as seen from Earth).
(a) The ratio between the radii of Mercury and the Sun, as seen from Earth, is 0.006, so the ratio between the cross-section of Mercury and that of the Sun is: _______
(b) The drop in solar power during a transit, in W/m2, is approximately equal to: _______
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