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Observation of the passage of Mercury

Observation of the passage of Mercury
Watching the passage of Mercury through a telescope is possible only through a dense dark light filter. Without such a filter to look at the sun is strictly prohibited to avoid loss of vision. To weaken sunlight, it is also useful to diaphragm a telescope lens up to 40 mm in diameter. When the telescope is magnified 25-30 times, the planet is visible in a small black circle and is clearly visible against the background of the solar disk.

But it is better and safer to observe this phenomenon on a solar screen, which is easy to make from a sheet of plain plywood or thick cardboard. The screen is covered with white paper and attached to the telescope pipe (perpendicular to its optical axis) with three or four guide bars (the screen can be moved along them, which allows obtaining an image of the Sun of the required size). Aiming the telescope at the sun follows its shadow on the screen. In order to see the course of the phenomenon better, it is useful to put (nude star videocelebs.net) a thick cardboard board on the end of the telescope where the lens is located, which partially covers the screen from diffused sunlight.

The simplest observations (but requiring great care) are reduced to registering the moments of contact of the disk of Mercury with the edges of the solar disk, they are recorded with an accuracy of 1 second on a well-calibrated clock, and even better - on a stopwatch.

To solve a more difficult task - determining the position of Mercury at different moments of its passage - it is necessary to draw a circle in the middle zone of the screen in advance, and pre-set its radius on the screen of the Sun. Most often choose a radius of 50 mm. In the process of observation, the image of the Sun is held on this circle and within it are marked by points of the position of the planet at different times, recorded on the clock with the same accuracy.

Astronomy lovers who can photograph can try to get pictures of various phases of the phenomenon. This requires a photographic camera with a high-speed shutter, which would allow for shooting with an eyepiece magnification and providing on the negative the dimensions of the solar disk at least 80 mm. Under these conditions, the diameter of the photographic image of Mercury will be about 0.4 mm. If the image of the Sun is smaller, then the disk of the planet may fail. To photograph a telescope lens, it is necessary to diaphragm up to 30 mm in diameter.

Focusing the camera is pre-held on the image of the moon on frosted glass and securely fastened. Photographic material should be of minimum sensitivity. Exposures (very short - tenths and hundredths of a second) are chosen empirically by repeatedly photographing the Sun several days before the passage of Mercury through its disk.

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