The full moon rises as the sun sets on the 14th day of the lunar month. A small telescope, such as the 70mm f.8.7 Televue Ranger I’m using for this series of sketches is a perfect instrument for full moon viewing. So are binoculars. The moon is [...]]]>

fourteen-day (full) moon

The full moon rises as the sun sets on the 14th day of the lunar month. A small telescope, such as the 70mm f.8.7 Televue Ranger I’m using for this series of sketches is a perfect instrument for full moon viewing. So are binoculars. The moon is a very generous target, and even the least expensive department store telescope will provide you many hours, days, months and years of inexpensive lunar observing fun!

The features you see on the full moon night are so different than the other nights. There are no shadows! So the features which stand out are the more reflective (bright white young craters and their ejecta) or the darker, less reflective mare.

Many new lunar observers think the full moon is too bright to view through a telescope. It’s not, but there are some tricks you can use to make your full moon view more enjoyable. One trick I like is to use a higher power eyepiece when viewing the full moon. That higher magnification dims the apparent brightness of the full moon. Another trick is to observe the full moon next to a streetlight or normal outdoor house lighting. We hate those lights when they ruin our dark skies, but they don’t hurt lunar viewing one bit, in fact they improve it! I don’t like to use moon filters or neutral density or polarizing filters when observing the moon. They diminish the sharpness of the features I want to view.

There are so many features I can identify on these sketches, but I’ll just mention the ones I have not covered before. My center sketch seems to be a little better than the “final” lower one. I can see, in addition to the great rayed craters Copernicus, Tycho and Kepler, lots of small bright white craters or ejecta. Proclus and Messier are near Mare Crisium, but it will take a map for you to find them. Proclus is a crater that is actually visible to the unaided eye at full moon, but I didn’t capture it on my sketch very well, probably because I made this sketch after midnight on a mid-week work night!

My photo of the fourteen-day moon

My Trapezium sketches

Galileo’s observed the Trapezium stars in the sword of Orion on February 4, 1617. He labeled the three stars “c”, “g”, and “i”. These stars are known now as the “D”, “C” and “A” components of Theta 1 Orionis, or 41 Orionis. He did not see the fainter [...]]]>

Galileo's Trapezium

My Trapezium sketches

Galileo’s observed the Trapezium stars in the sword of Orion on February 4, 1617. He labeled the three stars “c”, “g”, and “i”. These stars are known now as the “D”, “C” and “A” components of Theta 1 Orionis, or 41 Orionis. He did not see the fainter “B” component.

Galileo’s text states that the apparent spacing of stars “a” and “g”, as seen through his telescope, exactly matched the apparent spacing of two of the stars in Orion’s belt as seen with the unaided eye. This implies a power of 27 for his telescope.

This observing report from Galileo’s notebook is translated from the Latin: “The arrangement of fixed stars pictured here was discovered by me near the point of Orion’s sword, from which they arise toward the north and lean a bit to the east; and g and b appear equal in magnitude, a smaller really by little, but two, c, i, rather faint, scarcely a fourth or fifth part of g itself. Three, a, b, g, form a very obtuse angle. The lines through b, a, and through i, c, are almost parallel, but will [eventually] meet [in a direction] towards c, a. Two, c, i, are equidistant from g, which they practically touch. The distance between a and b is adjudged three semidiameters of Jupiter, to which the distance b-g seems triple. These things were observed by me the fourth day of February 1617 at Bellosguardo.”

I sketched the Trapezium using my 70mm Televue Ranger and two eyepieces — my 25mm Zeiss Abbe for a 19x and 16mm Zeiss Abbe for 30x magnified view. At 19x I had difficulty seeing the B or faintest component of the trapezium stars. But when I upped the magnification to 30x I could see all four stars easily.

Here is an astrophoto of M42, the Orion nebula, showing the Trapezium stars. It was taken by my hubby Morris Jones.

Here is Charles Messier’s sketch of M42 and the Trapezium stars

Here is a huge list of links, references and additional information about Galileo’s observations.

My sketch of the Pleiades

Galileo’s sketch of the Pleiades was published in Sidereus Nuncius in 1610.

Galileo identified four levels of stellar magnitude. He represented the six naked eye stars he could see with a large star symbol. These 6 stars were listed in Ptolemy’s Star Catalog. Next come seven stars [...]]]>

Galileo's Pleaids

My sketch of the Pleiades

Galileo’s sketch of the Pleiades was published in Sidereus Nuncius in 1610.

Galileo identified four levels of stellar magnitude. He represented the six naked eye stars he could see with a large star symbol. These 6 stars were listed in Ptolemy’s Star Catalog. Next come seven stars represented by larger than average star symbols. Twenty-one average sized star symbols are the next magnitude and two smaller than average star symbols complete the sketch.  Galileo saw thirty-six stars in the Pleiades.

My Pleiades sketch, using my Televue Ranger and a 25mm Zeiss Abbe Ortho eyepiece shows the Pleaides I was able to see at 19x. I saw the familiar 7 brightest members (the 7 sisters) and an additional 39 stars. I tried to make the size of each star sketch match the changes in magnitude, just like Galileo did.

Several of Galileo’s hand drawn sketches of the Pleiades, along with a diagram of Cassiopea, can be found in Volume 3, page 962 of the National Edition of Galileo’s works and are linked below:

Volume 3, page 962 of the National Edition of Galileo’s works

A page from Sidereus Nuncius showing Galileo’s Pleiads

Seven Sisters Overhead: Native American Legends of the Pleiades is an article I wrote for Fast Forward, a Marin County, CA Kids newspaper. It features a charming sketch of the Pleiades by my mom, Barbara Miller.

Here is a wide field astrophoto of the Pleiades or M-45 taken by my hubby Morris Jones.

sketch of 3-day old waxing moon 2-28-09

sketch of 5-day old waxing moon

sketch of 14-day (full) moon 3/11/09

Galileo’s watercolor drawings were made with brown ink wash on watercolor paper. To me, these are the most beautiful of Galileo’s astronomical renderings. When I look at the [...]]]>

Folio page 28 manuscript copy of Sidereus Nuncius

sketch of 3-day old waxing moon 2-28-09

sketch of 5-day old waxing moon

sketch of 14-day (full) moon 3/11/09

Galileo’s watercolor drawings were made with brown ink wash on watercolor paper. To me, these are the most beautiful of Galileo’s astronomical renderings. When I look at the lunar terminator through my own telescopes, and hunt for interesting features to sketch, I sometime daydream, and try to imagine what Galileo thought as he surveyed these surprising lunar features. I feel a tingle every time I see the sunrise or the sunset illuminate a lunar crater floor, or escape through a crumbling wall to create a fleeting sun ray.

I’ve been sketching the moon for about 20 years, but I’ve always focused on a small segment of the lunar terminator as my sketching target. I’d never tried to sketch the entire moon in one sitting before. Sketching the entire lunar disk is a daunting project. So I decided to make my sketches very small – three sketches to a page. I like to show my “rough sketch” first. It is sort of a outline of the major features. Then I create a finer sketch, filling in the details. Often, I make a third “final final” sketch, too.

I used a 5″ x 8″ inch bound sketch book instead of my usual 3.5 x 5 inch 400 Series Strathmore spiral bound sketch pad. I always use my slender set of 12 mix and match Pitt pure graphite, Castell fine, and Wasserlack bold Faber-Castell graphite art set pencils. I like to keep the sketching process simple and uncluttered and the supplies compact. No table, no lights shining off my forehead, no messy products that would get on my Zeiss eyepieces or my fingers. Armed with these supplies, all I have to do is wait for the moon to become visible on a night of above-average seeing.

Here is a partial collection of “cropped” lunar sketch pages made at the eyepiece of my 70mm Televue f/7.8 Ranger refractor. I haven’t completed my “Galileo-like” lunar sketches yet because I prefer to wait for those nights of exceptional seeing to sketch at the eyepiece, and I am in no hurry to finish this project. These crops don’t show the “rough” sketch, and are rotated to match Galileo’s brown ink wash paintings. There is one full sketch linked at the bottom of this article, and I’ll dedicate one future blog to each of the lunar sketches.

I used one of the finest planetary eyepieces to complement my telescope — a 25mm Zeiss Abbe Orthoscopic. This gave me a 19x view of the lunar surface, similar to what you would see through a pair of binoculars, but also similar to the magnification (but not the same field of view) of Galileo’s telescope, which was 21x. Twentieth century Extra-Low Dispersion (“ED”) glass in the Televue Ranger and the exceptional quality of the Zeiss Abbe orthoscopic eyepieces plus a wider field of view give me quite an advantage, but that’s the telescope and eyepieces I have at my disposal. Lucky me!

An example of my uncropped 3-to-a-page lunar sketches through a 70mm refractor

Galileo's 1609 telescope

There were separate housings at either end for the objective and the eyepiece

When I started thinking about how to integrate International Year of Astronomy into my 2009 What’s Up podcasts I naturally focused on Galileo’s first observations through a telescope 400 years [...]]]>

Galileo telescope replica and my TV Ranger

Galileo's 1609 telescope

There were separate housings at either end for the objective and the eyepiece

When I started thinking about how to integrate International Year of Astronomy into my 2009 What’s Up podcasts I naturally focused on Galileo’s first observations through a telescope 400 years ago. Over the first months of 2009 I had collected a gallery of Galileo’s first sketches, watercolors and engravings. These historic observations suggested a project I’ve been wanting to do for some time — to recreate all of Galileo’s astronomical sketches through a similar sized instrument.

Galileo made his first telescope, a spyglass that magnified 3x in June or July 1609. Next he made an eight-powered instrument and presented it to the Venetian Senate in August. His next telescope, which magnified twenty-one times is the one he used to observe the bumps and shadows on the moon, Jupiter and its moons, and individual stars within patchy nebulae. These first observations were unveiled to the world in his book, Sidereus Nuncius published in March 1610.

Galileo’s telescope, pictured above has a objective diameter of 37 mm and a focal length of 980 mm. The instrument’s magnification is 21. My Televue Ranger (ED Doublet Apochromatic refractor) has an objective diameter of 70mm, a focal length of 480mm, and using a 25mm Zeiss Abbe Orthoscopic eyepiece, yields a comparable magnification of 19. The field of view, however is dramatically different between the two instruments. Galileo’s longer focal length and smaller objective (which he also stopped down to lessen chromatic aberation) give a relatively small field of view  – 15 degrees. My shorter focal length and larger aperture instrument has triple that FOV.

What this means is that a telescopic view of Venus through both instruments will show the same size Venus, but in my ‘scope there will be more “sky” around Venus, and in Galileo’s there will be mostly Venus. A view of the moon is a different matter. Just a portion of the moon is visible at any one time through Galileo’s scope and the entire moon is visible through mine.

Galileo’s drawings and watercolor paintings of the moon inspired me to sketch what I see through the eyepiece. I’ve been sketching since first light with my own first telescope over 20 years ago. This year, I’ll be honoring Galileo and celebrating the 400th anniversary of telescopic observations by creating 21st century sketches through a small refractor. I hope this journey back 400 years to revisit Galileo’s observations encourages you to look up. And I hope you’ll enjoy my sketches standing side-by-side with these historic first astronomical observations through a telescope!

NPR story: Galileo’s Telescope Travels Far, Sees Farther

Galileo’s telescope: specifications and images