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09 January 2020

Take Your Telescope Out for a Stroll in the Universe

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Astronomy is one of the few sciences that is within our reach without specialised university training. To be an astronomer one only needs a passion for the cosmos and the sensitivity to be awed by starry nights. And although it is not essential, a good telescope is also recommended. Whether it’s a brand-new Christmas present or the one that —as a good New Year’s resolution— needs to be rescued from the attic where it’s been collecting dust, thanks to a telescope and with these simple tips we can move up to another level of enjoying the night sky.

The greatest discouragement for the novice astronomer is the lack of knowledge. This can happen when they are first introduced to the contemplation of the starry sky and also when they approach a telescope for the first time, since every scientific instrument requires some basic knowledge about how to handle it: how to mount it, how to calibrate it, how to point it and… at what? Above all, it is crucial to know where to look. Starting without that preparation is the first step for the telescope to begin its journey (back) to the storage room. On the other hand, excessive expectations can also be discouraging; a telescope is not a tablet through which spectacular images will emerge, like those seen in astronomy apps, documentaries or books.

Learning in the company of others

For these reasons, the best advice is to look for an astronomer friend. The best way to transmit the passion for astronomy is from person to person, under star-filled nights. In the absence of an expert among one’s family and friends, approaching a local astronomy association or club where they organise observations is a great way to get started in the use of a telescope. And if not, you can always do it on your own. With desire, a little patience and the many resources available on the Internet today, it is increasingly easy to learn how to operate the instrument that has most changed our view of the world and the universe.

Approaching a astronomy association where they organise observations is a great way to get started in the use of a telescope. Credit: Óscar Blanco.

It should be remembered that, without the aid of any optical instrument, it was merely by observing the movements of the Sun in the sky that Greek polymath Eratosthenes, in the third century BC, was able to prove that the Earth was round. Shortly afterwards, Hipparchus solved the distance from the Earth to the Moon, and even the size of the satellite, by observing the Earth’s shadow during lunar eclipses. It was Tycho Brahe’s observations, modelled on Johannes Kepler‘s mathematics, that put the Sun rather than the Earth at the centre of our solar system. All these discoveries were made with the naked eye and a little bit of mathematics.

We had to wait for Galileo Galilei, who in 1610 first used the telescope to scan the sky with some radical results. In just a few days, Galileo discovered moons orbiting Jupiter, phases of the planet Venus, mountains and giant craters on the Moon, that the fuzzy Milky Way was actually many stars, and he intuited that something strange was happening on Saturn. His optical instrument was a window to those other worlds that Giordano Bruno had imagined—a dangerous idea that led him to the bonfire and would truncate Galileo’s scientific career.

The most important thing about taking one’s first spin with a telescope

Galileo’s telescope was infinitely worse than any commercial telescope today. One of the most revolutionary experiences in the history of science is available to anyone, and it is no more expensive than any other hobby. However, the reality is that most telescopes bought with enthusiasm end up forgotten and collecting dust.

Preparation is essential to prevent one’s first experience with a telescope being frustrating. Learning how to correctly set up the telescope, the finderscope, the eyepieces —and the counterweights, if any— are the important first steps. It is necessary to practice this at home, spending time on each step, with the manual at hand and a good video channel on YouTube to help you.

Apart from this basic handling, planning the observation site is also crucial. The best telescope on the market in a big city is only good for seeing three objects. The most important thing is to look for the blackest sky possible, which is only achieved by moving away from the light pollution of the cities.

The first target is the Moon

Simulation of how the Moon looks through an initiation telescope, a 90 mm with a 20 mm eyepiece. Credit: Telescope Simulator

It’s the easiest celestial object to locate and certainly the most impressive. The lunar phase matters a lot: full moon days are not the best time in the lunar cycle; in contrast, the fourth crescent (and early evening) provides much more spectacular views. This is because, in this phase, the area that separates the illuminated hemisphere of the Moon from the dark zone (called the lunar terminator) shows the relief of the mountains and lunar craters. This is due to the shadows, which project the irregularities (invisible during the full moon phase).

Jupiter and Saturn are the next step. Locating them is sometimes not so simple, as they are often mistaken for very bright stars at night. To make it easier to find them, we can use a mobile app and then point the telescope. On Jupiter we can see four “little stars” around it: they are not really stars but rather its largest moons (Io, Callisto, Ganymede and Europa). And within the giant planet’s disk we can see bands of anticyclones and storms, stretched out by the planet’s enormous rotational forces. On Saturn, even the most modest telescopes allow us to see its ring system; it may be small, but we can spot it with a little effort.

On the left, photo of M42, the Orion Nebula. On the right, simulation of how it looks through an initiation telescope. Credit: Kees Scherer/Telescope Simulator

The Andromeda galaxy, the Orion nebula, and the Pleiades star cluster are other objects that look remarkably different when viewed through a telescope rather than the naked eye. It is important to first locate these smudges in the sky without the aid of any optical instrument before attempting to aim the telescope. When you succeed, you will see a rather humble image through the eyepiece (compared to what one sees in astronomical photos), but the sensation of observing these celestial objects directly is simply overwhelming.

And in the southern hemisphere, the Magellanic Clouds are two of the best targets for the telescope, which are also easily located with the naked eye over the northern horizon.

Borja Tosar


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