How to Observe the Sun

Coronado Solar ImageWhen we look up at the night sky, we can see celestial objects overhead constantly moving and changing. Believe it or not, the surface of the Sun is just as dynamic. Our closest star is burning at 5,778 Kelvin and its surface is dotted with solar storms, sunspots, coronal mass ejections, and other fascinating phenomena. All you need to discover this amazing world? A solar filter or dedicated solar telescope.

With a total solar eclipse on deck for August, 2017, there has never been a better time to get started with this rewarding hobby!

First, a Word about Safety

We can’t stress this enough: NEVER attempt to observe the Sun without proper protection for your eyes and telescope. Viewing direct, unfiltered sunlight (even for an instant) causes permanent, irreversible eye damage including blindness.

Do not use a Herschel wedge or projection method when observing the Sun with a nighttime telescope larger than 70mm. Doing so can cause heat buildup inside the telescope, damaging its optics. Always use a solar filter that filters the light before it enters the telescope. Never use a solar filter that attaches to an eyepiece as they can crack with heat buildup, allowing unfiltered light to pass through to the eye. Proper solar filters include: approved solar glasses or solar viewing cards, full aperture solar filters for nighttime telescopes, and specialized solar telescopes.

To prepare for solar viewing, remove finderscopes and secure solar filters to all telescopes before taking them outside. Finally, don’t forget to wear a hat and sunscreen! Although the safety concerns with solar observing are real, once you take these basic precautions, you’ll be ready to have a great time viewing the Sun.

White Light or H-alpha?

With a proper full aperture solar filter, virtually any telescope can become a solar telescope. These affordable filters from AstroZap, Baader Planetarium, and other manufacturers fit over the end of your telescope and lock in place with setscrews. These filters render the Sun in white light so it appears as a bright white disk. Sunspots can appear anywhere on the disk, in varying shapes and sizes.

White Light Solar ImageThe Sun in white light with sunspots. Captured a with 114mm ED refractor and DSLR.

To view solar filaments and prominences, you need to view a narrower spectrum of visible light. That’s where Hydrogen alpha solar telescopes come in. Coronado’s P.S.T. has been our choice for Solar Telescope of the Year for two years running. This compact, affordable solar telescope is engineered to allow only 1 angstrom of light at a very specific wavelength to pass through to the eye. When viewed through the P.S.T. or any other H-alpha scope, the Sun appears fiery red. With high magnification, you can view prominences along the edge of the solar disk and filaments scarring its face.

Coronado Solar ImageHydrogen alpha image captured with Coronado SolarMax II.

H-alpha telescopes go up in price very quickly as aperture and filtering precision increases. Coronado’s SolarMax II series are premium scopes that allow as little as 0.5 angstrom of light to pass through.

Using a Solar Finderscope

No matter which telescope you choose, you will need a solar finderscope to center the Sun in the eyepiece. These are usually included with an H-alpha scope or sold separately for white light observing. Unlike traditional finderscopes, you do not view through a solar finder. Instead, a pinhole on the front of the finder projects the solar disk onto a panel on the back. Line up the pinhole projection with the white dot on the back of the finder, and you’re ready to observe.

Capturing Images of the Sun

It’s perfectly safe to hold your camera or smartphone up to the eyepiece of your telescope or solar scope to capture images. You might be surprised how great the images actually come out! (A smartphone adapter or universal camera mount can help steady your shot.)

A dedicated astronomy camera like Celestron’s NexImage family of solar system imagers is a simple way to create even sharper, more detailed images of the Sun. These webcam-style devices capture hundreds of frames of video. Then, smart software automatically stacks the best shots while discarding shaky ones. The great thing about webcams is you can also use them at night to create photos and video of the Moon and planets!

As with any form of astroimaging, practice makes perfect. If you want to capture the 2017 eclipse, it’s a good idea to familiarize yourself with the process now, so you know what to expect on the big day. You don’t want to be fiddling with your gear at the crucial moment.

Get Your Gear Early

Solar telescopes and filters are highly specialized instruments that require longer manufacturing times than traditional telescopes. The wait only gets longer before key solar events like eclipses and transits. In other words, it’s never too early to purchase your solar telescope and accessories for the 2017 Total Solar Eclipse!

White light solar image during partial solar eclipse.


Hydrogen alpha images captured using a Coronado SolarMax II telescope. Courtesy Meade Instruments.
White light solar images taken with a 114mm ED refractor and Canon 350D DSLR. Courtesy Bryan Cogdell/Stellarscapes.