Gene Hanson Website - Beginner's Guide


Beginner's Guide

Solar System Overview

The Sun, Moon, and Planets - MAS images

The showcase objects of our solar system.


The Sun, Moon, Planets, and Meteors

When amateur astronomers are asked what got them into astronomy, the leading answer is seeing the moon in a telescope. Others will answer seeing Saturn and its rings or Jupiter and its moons in a telescope. Though the experience of viewing the moon is fairly universal, Jupiter and even Saturn are not. Some people are disappointed saying, "They're so tiny!" But a budding amateur astronomer will be awestruck by the view of them.

One great thing about observing the planets is that you don't need dark skies to enjoy the views. You don't need a location with few artificial lights and you don't need a moonless night. Venus, Jupiter, Saturn, Mars, and Mercury are the planets which are readily seen by the naked-eye and all of them at a casual glance look like stars. Their existence have been known through much of antiquity because their defining characteristic is that they don't stay in one position in the sky. In fact the name planet comes from the Greek and it means wanderer.



At the Milwaukee Astronomical Society we show objects in our telescopes during our Open House nights. When we show Saturn our visitors express one of these two: 1) "I can see the ring!", or 2) "It's so small!" or "Why is it so small?" This second points are not really wrong, but small is a relative term. Yes, it's small if you're comparing it to the large images that you find in books or the internet. To give you a good idea about the size of the various planets, here is what those objects look like at 100X. Note: the sizes you see on your computer screen or phone are probably not correct. In order to get the proper sizing, click here or on the image and you can download a properly scaled PDF. When you print that document, the sizes are to a scale that you then see at 10 inches.

100X Moon / Planet size comparison - MAS images


Astronomical Seeing

The Moon crater Clavius showing the effects of bad seeing. Once you see the Moon or planets at relatively high power you quickly get familiar with the concept of astronomical seeing. The air in our atmosphere is in constant motion. Sometimes it can be very calm while sometimes it's extremely turbulent, and it can be everything between. As you can see in the image of the moon crater Clavius the waves in the image which result in a loss of resolution. Adding more power only results in making the image even fuzzier.

Bad seeing versus good seeing - MAS imageThe drawings at the left show how the movement of the air in the atmosphere effects image quality. You cannot directly see this motion, but you can easily see the consequence. This bending of the light of a star is what causes them to twinkle. Turbulence also has the effect of larger star images whereas steadier air results in smaller star images. In this example you can see how it effects an image of Saturn.

The seeing conditions often depends on the position of your object. When looking straight up you're basically looking through 10 miles of atmosphere. At 45° you're looking through 15 miles. And as you near the horizon that figure rises to over 100 miles. So obviously you want to view an object, especially the moon and planets, when they are higher in the sky.

We talked about patience before and lunar and planetary observing is where patience is rewarded. Seeing is almost never a constant. Even when things are really turbulent if you keep looking there will be these golden moments (sometimes just a fraction of a second) when there is more clarity and sometimes that clarity can be stunning.


Planets. All about the planets, stats and observing tips.

Sun and Moon. Discussion about observing the Sun and Moon.

Solar Eclipses. All about solar eclipses.

Lunar Eclipses. All about lunar eclipses.

Meteors. All about meteors and meteor showers.