Minimum Telescope Size for a Decent Exploration of the Night Sky
The aperture size is what really matters
When we were children, many of us were fascinated about the night sky, the stars, and the planets, but not many of us had the chance to explore the sky with a telescope.
The fascination and curiosity about the stars are still present when we become adults, and at some point, some of us feel the need to do something about it.
This was my case too. I said to myself:
“If you can’t become an astronaut or an astronomer, at least you can buy a telescope and become an amateur astronomer.”
As a child, I used to spend many nights in the summer vacations watching the clear night sky with the naked eye, dreaming about humanity exploring all those stars, and hoping that one day I will see them closer…I know, I’m a dreamer. But I also know I am not the only one, as John Lennon said.
Have you ever looked at the night sky in the summer at 3 am, from an unpolluted area? If the sky is very clear, you can spot the Milky Way with the naked eye, and it’s breathtaking!
“The origin and evolution of life are connected in the most intimate way with the origin and evolution of the stars.” Carl Sagan
I only had the chance to own a telescope later in life, when I was over 30 years old, but the passion for looking at the stars remained the same as when I was little and my curiosity grew even bigger. In fact, it was so big that I didn’t sleep for two nights in a row looking for the perfect scope to fit my budget.
I said again to myself:
“That’s it, I’m gonna buy one of these things! You only live once!”
How did I get my first telescope?
Having just a very small budget (less than 100 dollars), I searched online for clues to see what would be the best product to choose, trying to avoid buying one that would not be enough for my expectations.
I know…the budget was really low, but I didn’t want to invest too much from the beginning. I wanted to start low and then upgrade later.
This budget allowed me to get only one of the models of 76 mm aperture size, with a focal length of 300 mm. All the others in the same price range were less than 76 mm.
Why choose a 76 mm aperture size?
From my research, I realized that 76 mm is the minimum aperture size needed to have a clear, luminous, and close enough view of the moon and the planets. You can start with this, and if you make stargazing a permanent hobby, the next step is to get a scope with a minimum of 150 mm aperture size. This one will help you to see nebulas, galaxies, and star clusters, and the prices begin at about 250 dollars.
Aperture size is the diameter of the main lens (or the mirror) and the diameter of the tube usually is adapted to this size. The larger the diameter is, the more light can be captured in the mirror that is found inside the tube and the more clear and luminous the image is.
For this reason, your first scope should be large in diameter, even if the length of the tube is short. It is better to be short and thick than to be thin and long.
I finally decided to order a 76 mm scope online. When it arrived, I was happy like a child. I couldn’t wait for the night to come so I can test it. I wanted to see what it means to see the sky through a telescope, and now I had the chance…finally!
“Not only do we live among the stars, the stars live within us.” Neil Degrasse Tyson
Refracting and reflecting telescopes
There are two main types of telescopes, according to the way they capture and focus light: refractors and reflectors. The difference between them is that refractors offer better contrast and the quality of the resulted image is higher because there are no light distortions.
The telescope I use is a reflector. As you can see in the images, the view of the Moon is of very good quality but has a little light distortion. When you see planet Venus, the light distortion is even more visible.
Being lucky to catch the Moon and planet Venus in my first night of exploration, the results were beyond expectations. The aperture size of 76 mm allows you to see clearly the surface of the moon and its craters. Seeing planet Venus is also a delight, but obtaining it requires more fine-tuning and patience.
You can also zoom in by changing the lens, but the image will be a bit darker and a bit blurry. It’s up to you how close you want the image to be. It is better to do this when you have a full moon.
With this aperture size, you will have a good look at the brighter stars, and you will also notice stars that are barely visible without a scope, or even invisible to the naked eye.
If you want to buy your first telescope, regardless if this is for yourself or for your children, it is great to start with a 76 mm. This will make you get used to exploring the sky, and later you can upgrade. Make sure it includes a Barlow lens that has to be 2x or more, for obtaining at least a double zoom.
Among the things that should be on anyone’s to-do list at least once in a lifetime is the use of a telescope. It is true that you can see NASA’s photos online, made with Hubble and other telescopes that are worth millions of dollars…but you experience a unique feeling when you spot the Moon or the planets with your own eyes, through the lens of your own telescope. It’s like there is something magical in seeing that real light. And it just makes you say “Wow!”.
Once I get a better scope, I will write another article that will show you what can be seen with it. I hope you enjoyed this one and that it awoke in you the desire to begin stargazing.
“The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.” Carl Sagan
Note: All the images in the article were shot with my phone by placing its camera on the eyepiece of my telescope. They are real photos made while I was stargazing with my 76 mm telescope (the one seen in the header image).
