Day Star

I didn't have a chance to do any stargazing last night, however, I was able to do a little stargazing yesterday afternoon. My Coronado Personal Solar Telescope (PST) is always set up on a camera tripod in our dining room ready to check out the star that powers all life on this planet - the Sun.

I saw several tall spikes along the Southeast limb (these were approximately 40,000-50,000 miles high) along with a huge prominence along the Southwest limb that looked like a wall (this prominence was approximately 60,000-80,000 miles high and just as wide). To put the size of these prominences in perspective, our Earth is just under 8,000 miles in diameter, so these prominences were massive. There was only one sunspot visible on the surface but, as always, the view was spectacular and awe-inspiring.

Prominences are gas eruptions that reach out from the surface of the Sun into space. Scientists are almost certain that these eruptions are caused by twisting magnetic fields, although the exact science behind their formation and life history is still to be determined. The Sun is a huge ball of gas with a core that is basically solid (14 times the density of lead) and it rotates faster at the center than at the poles. It takes about 25 days for a point at the equator to make a complete revolution and about 35 days for a point near the poles to make the same revolution. Because the Sun has a very strong magnetic field (as does the Earth), scientists speculate that this variance in the rotation rates twists and mangles the magnetic fields, causing most of the Solar activity we can observe - prominences, sun spots, Solar flares and Coronal Mass Ejections.

With my PST, I can routinely observe prominences, filaments, sun spots, plages and surface granulation. Prominences are gas eruptions viewed along the perimeter of the Sun against the black of space, and so stand out very well with great detail. When the same eruptions are viewed directly above the Solar disc, they are called filaments and look like large cracks in the surface. Prominences live for a couple of hours to a couple of weeks and therefore, its usually not possible to see them change shape in a single observing session. But over time, changes can be observed and they come in many different shapes and sizes. I have seen prominences that look like trees, fountains, clouds floating in space, loops, spikes and more. One of the coolest things Ive seen is a prominence with the upper part broken away from the base floating off into space.

Sun spots in the PST are little black dots, each one about the size of Earth, in other words, tiny pinpoints. Sun spots are cooler areas on the surface and they usually form in pairs which are oppositely charged - one positive and one negative. The sun spots go through an 11 year cycle and right now, we are at Solar Minimum with very few sun spots and relatively low Solar activity. For the next four or five years, Solar activity will be on the rise and Im really looking forward to following this progress in my PST. I just bought the scope last year and I havent had the chance to see the Sun in a really active period. I can also observe plages, which are hot spots that surround sun spots and appear almost like ripples in water. They are much lighter in color than the rest of the surface. Surface granulation is also visible in the PST which is called the orange peel effect. Most of the surface of the Sun is boiling in huge convection cells very similar to boiling water except at a much slower rate and on a much greater scale. Solar flares are also visible in the PST but it takes a lot of luck to see these. Unlike prominences, these happen very quickly so you have to be looking at the right time to observe one and I have yet to do so.

I love stargazing at night but the view is almost always static, unless a meteor shower is going on or a satellite passes overhead (or through your eyepiece!). The view of the Sun changes on a daily and sometimes hourly basis and so is very dynamic and exciting to watch. If youd like to see some really spectacular solar imagery, you can visit the website of the Solar and Heliospheric Observatory at The SOHO is a space telescope like the Hubble telescope except that its much farther away from the Earth and it only watches the Sun, along with any comets or planets that happen to be near the Sun. At the SOHO website, youll see images taken at different wavelengths which means you can view different aspects of Solar activity.

The Sun is so active because it is powered by nuclear fusion. It is a ball of gas about 865,000 miles in diameter (109 times the diameter of the Earth). It consists mostly of hydrogen gas and at the core, the pressure and the temperature are so great that hydrogen atoms are being fused into helium atoms and as a result of that fusion, light and energy are created. That light and energy power all of life on Earth and the same nuclear fusion powers all of the other stars we see at night. The Sun was formed along with all of the rest of the Solar System (the planets, moons, comets, asteroids) about 4,500 million years ago and will last about another 5,000 million years. Once the Sun fuses all the hydrogen into helium, it will start fusing helium into carbon and will swell into a Red Giant that will eventually vaporize the Earth, possibly even engulfing it.

When stars are more massive than the Sun, they have enough energy to keep fusing fuel after all the hydrogen is gone. If massive enough, stars will fuse helium into heavier elements such as carbon, neon, oxygen and silicon all the way up to iron. But no star can generate enough energy and heat to fuse iron into a heavier element, and so when these really massive stars exhaust all of their fuel and all that remains is an iron core, they will then collapse and explode in a cataclysmic explosion called a supernova. The heat of this supernova will create all of the known elements in the Universe heavier than iron. Scientists theorize that there was a large supernova explosion nearby right before the formation of our Sun and the Solar System. That explains the existence of all the heavier elements that we find on the Earth. This explanation of stellar fusion that I have just outlined is greatly simplified. If youd like to learn more, you can visit a website explaining nuclear energy at

The Sun in my PST shows as a red ball. The red color comes from an h-alpha filter that allows me to see the fine detail of the prominences and filaments. The h-alpha filter shows only a very narrow band of light and needs to be manufactured to tolerances much greater than that of a standard telescope mirror or lens. Until a few years ago, an h-alpha filter costs thousands of dollars and was out of the reach of most amateur astronomers. The PST came out a few years ago for a price of $499.00 (it is now $599.00) and made Solar observing affordable for many people such as myself. It is a lot to pay for a dedicated scope, however, I havent regretted my purchase a single day. I should point out that white light filters are available for almost any telescope at a much lower cost. White light solar filters show sunspots and some solar granulation as well as limb darkening, which a subtle effect seen near the perimeter. I used a white light solar filter with my Celestron C5 telescope for a while and greatly enjoyed the view. If you have a small refractor, you can also project the image of the sun against a piece of white cardboard to see sun spots. Its not advised to use the projection method with reflectors because you are greatly magnifying the heat of the Sun and may damage the scope.

I have done some sidewalk astronomy with the PST, but it is more difficult showing the Sun as compared with showing the Moon or Saturn. One problem is that everyone knows youre not ever supposed to look at the Sun so I often need to explain that its perfectly safe and sometimes even put my eye up to the eyepiece to show them it really is safe. Another difficulty is that even at high power, the view of the Sun is quite small and prominences are not really obvious at first glance. It takes some coaching to get most people to see the finer detail. I also take along a large photo of the Sun with various details pointed out, along with a small dot representing the size of the Earth to give viewers a better idea of scale. Once people see the fine detail and understand the scale, they are usually impressed and a few will even get excited. However, its no match for Saturn (see my essay called Saturn Rising).

There is a saying among amateur astronomers that the best scope is the one you use the most. If that is true, I would have to say that of the seven scopes I own, the PST is the best. It is definitely the most fun!

To see some great images of the Sun, visit SOHO.

Sidewalk Astronomer
A Drop of Water
Saturn Rising