Man’s farthest curiosity — the telescope
1. The origin and development of telescopes
Man’s farthest curiosity — the telescope. In 1608, Hans Liebsch, an optician in the Netherlands, built the first telescope inspired by his chance discovery that distant objects could be seen with two lenses. In 1609, Galileo Galilei from Florence, Italy invented the 40 times double mirror telescope, which was the first practical telescope put into scientific application.
In 1609, Galileo Galilei from Florence, Italy invented the 40 times double mirror telescope, which was the first practical telescope put into scientific application.
The telescope was one of the central instruments of the so-called scientific revolution of the 17th century. It revealed unprecedented phenomena in the sky and had a profound impact on the debate between followers of traditional geocentric astronomy and cosmology and those who supported the Copernican heliocentric theory. It was the first extension of the human senses, showing that ordinary observers could see things the great Aristotle could never have dreamed of.
2. Basic functions of telescopes
A telescope has three basic functions – light focus, resolution, and amplification.
Concentrating power is a measure of how much light an objective lens (the primary mirror in a mirror, the lens in a refractor) can collect from a distant object. Nominally, it is proportional to the square of the diameter of the aperture. Doubling the aperture results in collecting four times as much light.
Resolution is a measure of the amount of detail that is likely to be seen in an image. Nominally, it is proportional to the diameter of the aperture. Ideally, doubling the aperture solves half the size of the detail.
Magnification is not an inherent property of the telescope, but something the telescope must do in order to see anything through it. In other words, the image produced by the telescope’s optical system must be large enough that you can see the details in it. As we’ll see later, there are upper and lower limits to how much magnification you should use visually.
3. Type of telescope
There are three main types of telescopes, which differ in the way they collect light to form images:
The refractor telescope was the first telescope to be invented by Dutch lens maker Hans Lippershey in 1608. They have a curved lens at one end that focuses light along a long tube to a second lens, called an eyepiece, which magnifies the picture. Astronomer Galileo Galilei was the first person to look at the night sky through a telescope, discovering craters on the moon, Saturn’s rings, and four of Jupiter’s largest moons.
Reflective telescopes are sometimes called Newtonian telescopes, named after their inventor, Isaac Newton, who built the first one in 1668. They use mirrors to collect light and focus it on eyepieces. Mirrors are lighter than lenses, and they’re also easier to shape into a smooth, perfect surface. If there is any defect in the telescope’s optical elements, the image created will be distorted or out of focus and blurred.
The refraction telescope, invented in the 1930s, is the most modern telescope design. They combine lenses and mirrors to focus light onto the eyepiece. These telescopes are usually short and thick, a compact design that makes them easy to transport and handle. The optics are arranged so that light rays “fold” over themselves, making them focus, without passing through the full length of a long telescope tube, as traditional telescopes require.
4. The role of the telescope
The first function of a telescope is to magnify the angles of distant objects so that the human eye can see at even smaller angles. The second function of the telescope is to direct the beam of light collected by the objective lens into the eye, which is much larger than the diameter of the pupil (up to 8 mm), allowing the observer to see faint objects that would otherwise be invisible.
5. Telescope maintenance
First, keep the telescope in a ventilated, dry and clean place to prevent mildew. If possible, put a desiccant around the telescope and change it frequently.
Second, the residual dirty points or stains on the lens, to use a professional cleaning cloth gently wipe, so as not to scratch the mirror, such as the need to clean the mirror, should use cotton accounted for a little alcohol, from the center of the mirror along a direction to the edge of the mirror wipe, and constantly replace cotton ball until wipe clean.
Third, the telescope belongs to the precision instrument, do not throw, heavyweight, or do other violent actions to the telescope.
Fourth, non-professionals should not attempt to disassemble the telescope or clean the inside of the telescope themselves.
Fifth, we should pay attention to moistureproof and waterproof when using telescopes. As a precision instrument, the telescope should be avoided in harsh conditions.