Telescope Night Information

Welcome to Dyer Observatory’s monthly Telescope Night.  During this event, visitors will have the opportunity to view up to several objects through Dyer’s various telescopes, explore our unique exhibits, and chat with astronomy staff and volunteers while getting your burning astronomy questions answered.  There is not a set program for the event – just wander around and enjoy all that we have to offer.  Below is a list of *possible* targets for telescopes this evening, a map of key points of interest at Dyer, and a handy sky chart for what is above us tonight.  If clouds intervene, we will still have the historic Seyfert Telescope available for visitors to check out and learn about.  Enjoy your visit!

International Space Station Flyover Tonight 9:22PM-9:27PM

If clouds aren't too thick, we have the opportunity to see the International Space Station fly by starting at 9:22PM.  It will appear in the low in the southwest, get about 45° above the northwestern horizon, and eventually disappear into the trees up toward the northeast.  The patio at the observatory front entrance would be a great spot to observe its passage.

Possible Telescope Targets

  • The Moon
    The Moon as we see it tonight.  Credit NASA SVS
    The Moon as we see it tonight.  Credit NASA SVS

    At a distance of 245,000 miles (402,000 km), the Moon, passing through the constellation Virgo tonight, is currently in a waxing gibbous phase and will reach full moon Monday. With a diameter of about 2,200 miles (~3,500 km), Earth’s moon Luna is the fifth largest moon in the solar system. A big misconception about the Moon is that we see various phases because the Earth casts a shadow on it. In reality, the phases are because half of the Moon is always illuminated (the half that happens to be facing the Sun, which changes over time as the Moon orbits the Earth), and we see varying amounts of the day/night side. Since Earth’s shadow is directly opposite the Sun, the only time the Earth could cast a shadow on the Moon is during full moon, when we see it completely illuminated! There is only one case in which the Moon does fall in Earth’s shadow - during a lunar eclipse. The Moon has two main areas of interest – the lunar highlands and maria. The highlands are the ancient, cratered surface of the Moon, whereas the maria (Latin for “seas”) are giant impact craters filled with solidified magma. The maria are much smoother because they were formed after much of the leftover debris from which the planets formed had already impacted the Moon and other bodies. Thus, there were craters where the maria are today, but they were erased when larger bodies impacted.

  • The Cat's Eye Nebula (NGC 6543)
    The Cat's Eye Nebula as seen with Dyer Observatory's Seyfert Telescope. Credit: Billy Teets
    The Cat's Eye Nebula as seen with Dyer Observatory's Seyfert Telescope. Credit: Billy Teets

    Found among the snaking body of the constellation Draco, the Cat’s Eye Nebula, formally known as NGC 6543, is a grand example of a planetary nebula. Despite the name, this type of object has nothing to do with planets except for a somewhat similar appearance to some of the planets in a telescope. What we’re are actually seeing is the remains of a small star that has met its demise. Though many mistakenly believe that all stars explode when they expire, the majority of stars are too small to undergo supernova explosions in their final moments. Most stars, including our own Sun in five billion years, will go through a couple of stages of swelling to many times
    their original size. At this point, the outer layers of the star are very weakly held by the gravity of the collapsing core and are gently lost to space over thousands of years. During this process, the white-hot core, known as a white dwarf, is exposed to space. The copious ultraviolet light emitted by the small core is absorbed by the expanding outer layers, causing them to fluoresce like a cosmic neon sign. The white dwarf, seen at the center of the nebula, is the size of our planet, but a spoonful of it on Earth would weigh as much as an elephant!

  • M13 - The Great Hercules Cluster
    The Great Cluster in Hercules. Credit: Martin Pugh
    The Great Cluster in Hercules contains around 300,000 stars and is the farthest object visible to the unaided eye that is also part of the Milky Way. Credit: Martin Pugh

    The Great Cluster in Hercules, also known as Messier 13 or M13, is one of 150 or so known globular clusters that mostly orbit the Milky Way. This cluster is densely packed with about 300,000 stars in a sphere 150 light-years wide. By comparison, there is less than one percent of this number of stars surrounding our Sun in the sphere of the same size. At an age of more than 10 billion years, globular clusters like M13 are some of the oldest objects known. When astronomers mapped the locations of globular clusters on the sky and incorporated their distances to determine their physical locations in space, they found that the clusters had a fairly spherical distribution and that our solar system was offset from the center of that sphere. It was deduced that the distribution’s center coincided with the center of the Milky Way galaxy, which gave us one of our first estimates of how far we were located from the center of our home galaxy. On a clear, dark night, M13 is visible without a telescope, appearing as a fuzzy star in the “keystone” of Hercules. At 25,000 light-years distant, it is the farthest object associated with the Milky Way that one can see with the unaided eye.

  • Porrima
    The Porrima double star system as seen over 15 years. Note the rings around the stars are an artifact of light interacting with the telescope optics and not objects surrounding the stars. Credit: Damian Peach
    The Porrima double star system as seen over 15 years. Note the rings around the stars are an artifact of light interacting with the telescope optics and not objects surrounding the stars. Credit: Damian Peach

    Observe a random sampling of stars in the sky and you might be surprised just how many of them are not living their lives solo.  Many stars are in fact double stars or systems with even higher numbers of members.  Some stars, even with the most powerful telescopes, may appear singular, but the signals encoded within the light coming from them will betray the presence of another star.  This is often because we are either too far from the stars to separate them or one star's bright glare overwhelms that of its partner.

    Porrima, also known as Gamma Virginia, is a great springtime double star.  It is one of brighter stars of the constellation Virgo and is located to the northwest of the constellations's brightest star, Spica.  Only 39 light-years away, it is binary star system that consists of two nearly identical stars, each with a mass and radius about 1.4 times that of the Sun.  With a temperature about 1,000K hotter than our Sun, they each emit about four times as much light as our own Sun.  The two stars are relatively close together as well.  As they orbit over a period of 169 years, they can come as close as 5AU (1 AU is the average Earth-Sun distance) of one other and move as far apart as 82AU (four times Pluto's average distance from the Sun).  For roughly a decade starting around 2010, the two stars were at or near their point of closest approach, making it possible to see them as separate stars only in the largest telescopes.  Now they have moved far enough in their orbits that modest telescopes can resolve them as separate stars.  Tonight they will appear like a small pair of headlights floating in the vast black cosmos.

Key Points of Interest

The map below will provide locations for key points of interest in the observatory.  If you have any questions, please don't hesitate to ask a staff member or volunteer.Dyer floor plan

  1. Garland Collection - Many of the original astronomy instruments obtained by Chancellor Landon Garland in the 1870s for use in the first physics and astronomy classes of Vanderbilt University.
  2. Star Model - An interactive model that displays information and positions of the 100 nearest and 100 brightest stars in the night sky as well as information about our own star, the Sun.
  3. Fused-Quartz Mirror Disk - One of two original, uncoated test mirrors for the 200" Mount Palomar Observatory that were given to Vanderbilt University. One was originally intended to be used in a new telescope of Vanderbilt University.
  4. Seyfert Telescope - On clear nights, the 24" Seyfert Telescope will be viewing a selected target. On cloudy nights, the doors will be open for visitors to see and learn about Dyer's largest telescope.
  5. Hallway Images - Large infographics about galaxies, the Milky Way, and the life cycles of stars. On the opposite wall is a high-resolution panorama of the Milky Way with constellations and deep-sky objects highlighted.
  6. HST Model & Planetarium Dome - Learn about the Hubble Space Telescope with the 1/5th scale model suspended in Dyer Observatory's original planetarium dome and experience the dome's acoustics.
  7. AstroCantus - A combination of art and science, AstroCantus is a series of chimes that sound as the stars pass overhead. NOTE: The chimes may be muted - ask a volunteer.
  8. ViewSpace Presentation - A presentation from the Space Telescope Science Institute. The program consists of continuous presentations ranging in length from five to 20 minutes and covering a variety of topics. Visitors may come and go as they please during the presentation.
  9. Meteorites & Tektites - A collection of various types of meteorites and tektites.

Sky Chart for May 9, 2025

Sky Chart for May 9, 2025 at 10pm CDT with ISS pass.
Sky chart for May 9, 2025 at 10pm CDT with ISS pass in beige.
 
To use this sky chart, hold it up to the sky so that the direction labels are aligned with the cardinal directions.  If you want to see what is in one particular direction, hold the chart out in front of you and rotate it so the label for the direction you are facing is at the bottom.  For example, if you are looking north, then you will turn this chart upside down so that the “N” is at the bottom of the page.
 
The sky shown in the chart is what one would observe at the following dates and times:
  • April 24th – 11:00PM CDT
  • May 9th – 10:00PM CDT (The Moon/planets are shown for this date)
  • May 24th – 9:00PM CDT

Deep Sky Objects

The objects listed in red are some of the brighter deep sky objects – objects that are outside of our solar system and aren’t single stars.  These are just a few of the 109 Messier objects – bright “fuzzy” objects that Charles Messier noted positions of as he was scanning the sky for comets during the late 1700s and early 1800s.  The 109 objects, each of which has a number preceded by a capital “M,” consist of star clusters, different types of nebulae (emission, planetary, and supernova remnants), and galaxies.  These are among the brightest and most easily observed objects by both amateur and professional astronomers. 

Stars and Constellations

This sky chart only shows a couple hundred stars that are visible to the unaided eye under dark conditions.  Some of the brightest stars have their names shown in bold.  Many others have names that were given to them by ancient astronomers, while others simply carry a catalog name/number.  The apparent size of the dot representing a star tells you about its brightness – the brighter the star, the larger the dot.  Sirius is the brightest star in the night sky.
 
The fall-winter sky contains a number of famous constellations that are visible from Tennessee.  Many, such as Orion, Taurus, and Gemini, have Greek mythologies behind them.  To the south are some not-so-familiar constellations, such as Antlia and Pyxis, which represent an air pump and mariner’s compass, respectively. In all, 15 of the southern constellations that are recognized by the International Astronomical Union (IAU) were established by French astronomer Nicolas-Louis de Lacaille during his expedition to the Cape of Good Hope in 1750.  

General Information About the Sky

The ecliptic is the imaginary line that the Sun follows through our sky. In reality, this line is dictated by the orbit of the Earth. Since all of the planets of the solar system lie in nearly the same plane, one will observe the planets positioned very close to or on this line as well. Because the Moon’s orbit is tilted just a bit more than five degrees to this line, the Moon will not stray far from the ecliptic either. Some objects, such as comets, will not stay around the ecliptic. The constellations through which the ecliptic passes are the 12 famous zodiac constellations. There are, however, 13 constellations through which the Sun passes. For the first two weeks of December, the Sun is located in the constellation Ophiuchus, the serpent bearer.

There are 88 official constellations that cover the entire sky. Some are never visible from Tennessee as we are too far north; however, some, such as Ursa Minor and Camelopardalis, are circumpolar – they never get low enough in the sky to disappear below our horizon. The rest of the constellations are seasonal and visible in the evening sky for certain months of the year. Constellations are not just the stick figures we sometimes imagine connecting the brighter stars but are instead entire areas of the sky – everything is in a constellation. Objects outside of our solar system (stars, nebula, clusters, galaxies) remain in constellations, but the Moon, Sun, planets, comets, and asteroids all move through the constellations over time. Some famous star formations, such as the Big Dipper, Little Dipper, and Great Square of Pegasus, are not constellations – they are very recognizable parts of constellations known as asterisms. The Big Dipper, for example, is just a part of the constellation Ursa Major, the great bear.

Our Sun is just one of about 300 billion stars that make up our home galaxy, the Milky Way (shown in light grey in the sky map). In the late evenings of winter and summer, the Milky Way can be seen overhead. In the late summer, we are looking towards the center of the galaxy, which appears somewhat brighter. In the late winter, we are looking away from the center. Our solar system is situated on its side about halfway out from the center of this barred spiral galaxy.

When the Milky Way is easily visible, we have an opportunity to see many examples of the different types of objects found in the disk of a spiral galaxy. Spiral galaxies contain large amounts of dust and gas from which stars can form. As these clouds of material, known as nebulae, begin to collapse, denser pockets within the nebulae collapse faster to produce stars. When the stars begin to shine, they illuminate the clouds from which they formed. A prime example for late autumn to early spring is the Great Orion Nebula (M42), which forms the second “star” in the sword of Orion, the hunter. As time goes on and star formation uses up the remaining material of a nebula or disperses it, all that will eventually remain is a cluster of a few hundred to several thousand stars. These clusters, known as open clusters, are dominated by hot, blue-white stars and highlight the spiral arms of galaxies like our own. The Pleiades Cluster (M45), also known as “Subaru” or the “Seven Sisters,” is a beautiful example of such a cluster. The proximity of the cluster makes about six of its members easily visible to the unaided eye, but a low-power telescope will show dozens more.

The more massive a star is, the shorter its life will be. Massive stars therefore do not have enough time to venture far from the disk of the galaxy before ending their lives in spectacular supernovae. One such star, which was observed to explode in 1054 A.D., formed the Crab Nebula (M1). Most stars, however, are not massive enough to die explosively; instead, they puff up to become red giants and then gradually shed their outer layers over thousands of years. Once the core of the dying star is exposed, its ultraviolet light causes the shed layers to fluoresce, producing a beautiful planetary nebula. These nebulae have nothing to do with planets, rather their shape sometimes resembles the outer planets. Excellent examples of planetary nebulae are the Ring Nebula (M57), Clown Nebula (NGC 2392), and Cat’s Eye Nebula (NGC 6543).

During the late spring and autumn, the Milky Way appears closer to the horizon. Our galaxy, like all spiral galaxies, is shaped like a disk and is fairly thin compared to its width. As a result, when we see the Milky Way near the horizon, we are able to look up and out of our galaxy relatively easily to see objects outside of it. These include other spiral galaxies, like the Whirlpool (M51) and Andromeda (M31) galaxies, and spherical- to football-shaped galaxies known as elliptical galaxies, such as M87. Orbiting around these galaxies are globular clusters such as the Hercules Cluster (M13) and the Pegasus Cluster (M15). These clusters contain anywhere from a few hundred thousand to over a million stars in a small volume.