Planetary Pursuit

In this episode, Planetary Pursuit . . . 

“We are voyagers on Earth sailing through space, like passengers on a ship, and many of us have never considered any part of the vessel beyond the cabin we occupy.” –S. P. Langley

Hello, everyone, and welcome back to On the Fly! Today, we're diving deep into planetary observing with my Celestron 500mm f/5 refractor telescope. We'll cover telescope basics, different eyepieces, the planets, and how to use 40mm, 25mm, and 10mm eyepieces to reveal stunning views of our celestial neighbors.

1. Learn the Night Sky; Before standing in the dark, wondering what to do, download "The Planets” app (free) on your smartphone or tablet to locate and identify each planet and when it’s visible.

Modern telescopes feature computer-aided go-to functions, but you'll pay considerably more for one with this capability. This may lead to frustration when the telescope doesn't perform as expected. However, remember you have a smartphone, and the Planets app is free; start with that instead.

2. Understanding Your Setup: Let's start with a quick overview. A 500mm f/5 refractor is a powerful instrument with a wide aperture, ideal for viewing planetary details. The 'f/5' indicates a fast optical system, offering a brighter image and a wider field of view. With this telescope and a combination of eyepieces, you can expect magnification ranges from 12.5X to 50X. Don’t be disappointed; this gives you great views of the planets with a telescope that will not break the bank.

When I purchased this instrument (~2000), it came with 25mm and 10mm eyepieces. However, adding a 40mm eyepiece offered a more expansive, low-power view, ideal for locating planets in the sky and orienting yourself. This saved me a lot of frustration trying to find an object magnified too high.

A few years ago, I upgraded my 25mm eyepiece to a Celestron X-Cel LX Series Eyepiece to improve image quality. This eyepiece offers a good balance of field of view and magnification, which is ideal for initial observations and enjoying larger planetary disks like Jupiter.

Here’s the challenge: when you start looking at eyepieces, you can quickly go down a rabbit hole of expensive options. I suggest not getting fooled by ads that say 2000 times magnification. The image distortion, complications, and frustrations are too problematic.

The 10mm eyepiece provides higher magnification, enabling you to focus on finer details such as Jupiter's bands and Saturn's rings. It’s thrilling to experience this for the first time.

3. Planetary Targets: Before viewing any object at night, align your telescope (during the day) with the finder scope that came with it. However, replacing that finder scope with a Celestron Starpointer Finder Scope ($23.95) simplifies alignment and makes locating objects at night easy. For too many years, I struggled with the original finder scope that came with my telescope.

This month, January 2025, let's concentrate on these planets; here’s what's visible–

1.     Jupiter: Currently well-placed for viewing, look for its four Galilean moons and try to spot its cloud bands.

2.     Saturn: Its rings are a must-see! The 25mm and 10mm eyepieces will provide excellent views.

3.     Mars: Even though it may not be at its closest, you can still observe its reddish hue and some surface features.

4.     Venus: It's the brightest in the night sky. Observe its phases, such as how we see the Moon.

Moon & Venus

Observing Tips:

Allow your telescope to cool to ambient temperature before observing to minimize image distortion.

Use a sturdy mount (or tripod) to minimize vibrations; eliminating vibrations is impossible. The image may appear blurry, so remove your hands from the focus knob and allow the telescope to stabilize. Carefully focus each planet using the telescope's focuser. This can be challenging at higher magnifications; adjust–allow the scope to settle–and then readjust until you achieve satisfactory results. You'll need to make slight changes as the Earth rotates.

Planetary viewing can sometimes be challenging due to atmospheric conditions. Don't get discouraged!

Using Your Eyepieces: Let's break down how to use each eyepiece:

First, if you want to calculate the magnification of your telescope with different lenses, here’s the formula:

Focal Length of the telescope / focal length of the eyepiece.

For example: 500 mm / 25 mm = 20X (That’s 20 times what you see with your eyes).

40mm (12.5X): Start with this for easy location and initial viewing.

25mm (20X): This will increase magnification for a more detailed look at Jupiter.

And 10mm for the highest magnification (50X); use this to try and spot finer details on planets like Saturn's rings.

Safety First: Never look directly at the Sun through your telescope. Use proper eye protection when observing the Sun (if you have a solar filter specifically designed for your telescope). Be mindful of your surroundings and observe from a safe location.

This podcast invites you to pursue the exciting wonders of The Planets using a refractor telescope. Here’s to wishing you clear skies and happy planetary pursuits.

I’m Patrick Ball; thanks for listening; see you in the next episode.