<< TO DO >>: Notes in ROUGH DRAFT ...

The information in these notes should not duplicate what is found under the specific objects observed during this program ... rather, these notes should supplement the objects' information with regards to the topic of this program... and provide hyperlinks to the object pages that will be used during this program:

These notes are still in DRAFT...

Some "Stars" of Astronomy

During this program, we will observe celestial objects that are related to the studies of several famous astronomers. Each person had a key idea in the history of astronomy. When we look at Saturn, for example, we will talk about Christiaan Huygens, the Dutch astronomer who first figured out that that funny thing around Saturn is in fact shaped like a ring.

Some "Stars" of Astronomy
Observing List


    Huygens  Shapley       Bethe      Hubble       H-R  Herschel      Foucault

Sep. 2 Saturn Albireo M11 M27 Earth 3 Saturn Albireo M11 M27 Earth 4 Saturn Albireo M11 M27 Earth

23  Saturn    M15     Albireo             M27      Earth
24  Saturn    M15     Albireo             M27      Earth

30  Saturn        Albireo       M31    M11         Earth

Oct. 1 Saturn Albireo M31 M11 Earth

 7  Saturn    M15     Albireo             M27      Earth
 8  Saturn    M15     Albireo             M27      Earth

21  Saturn        Albireo       M31     N 7662     Earth
22  Saturn        Albireo       M31     N 7662     Earth

28  Saturn    M15     G And       h & X        Earth
29  Saturn    M15     G And       h & X        Earth

Nov. 4 Saturn G And M31 N 7662 Earth 5 Saturn G And M31 N 7662 Earth

25  Saturn    M15     G And       h & X        Earth
26  Saturn    M15     G And       h & X        Earth

Dec. 2 Saturn G And h & X N 7662 Earth 3 Saturn G And h & X N 7662 Earth

HARLOW SHAPLEY
M 15
GLOBULAR STAR CLUSTER


Right Ascension:    21h28m49s           Best Seen:  8/15 - 12/1
Declination:        12o03'28"           Magnitude:  6.5
Constellation:  Pegasus

    Actual


Distance    42,000 l.y.
Diameter    130 l.y.
Total Luminosity    200,000 Solar Lum.
Number of Stars ~100,000
Age     12-15 billion years

WHAT TO LOOK FOR THROUGH THE TELESCOPE:

1.Recommended eyepiece: 40mm or 80mm

2.Through the telescope the cluster will appear similar to a pile of sugar or salt on a table.

SOME "STARS" OF ASTRONOMY INFORMATION:

1.The globular clusters (there are about 120 of them) lie clustered around the center of our Galaxy. Unlike most single stars, they can be found far above and below the Galaxy's disk.

2.Harlow Shapley used the globular clusters to find the direction and distance to the center of the Galaxy. Noticing that the globulars seemed clustered in the sky toward the constellation Sagittarius, Shapley reasoned that the Galactic center was in that direction, and that the globular clusters lie clustered around it.

3.Shapley found Cepheid variables within the globular clusters, and used them to measure the distances to dozens of globulars. He found that the globular clusters do seem to be grouped about a particular point in space--but that central point is a very long way from the solar system.

4.It had been previously thought that we lie near the Galaxy's center. Shapley showed that we are nowhere near the center of the Galaxy.

5.The center of the Galaxy lies about 30,000 light years away, in the direction of the constellation Sagittarius. Shapley overestimated this distance because he did not take into account the light-absorbing effect of interstellar dust.

ADDITIONAL HARLOW SHAPLEY INFORMATION:

1.Born November 2, 1885, in Nashville, Missouri. Died 1972. Studied at Princeton under Henry Norris Russell.

2.Shapley did much of his work between 1921 and 1952, when he was director of the Harvard College Observatory.

3.Shapley was deeply involved in the debate over the "spiral nebulae," such as M31. Are these small nearby objects within our own galaxy (wrong), or are they vast star systems like our own Milky Way seen at enormous distances (right)? The size of the universe was at stake, so it was a fierce debate. Shapley picked the wrong side.

ADDITIONAL GLOBULAR CLUSTER INFORMATION:

1.Globular clusters are found in the galactic halo - above and below the plane of the Milky Way.

2.These clusters contain about 100,000 stars.

3.The cluster has kept its shape for 10 to 13 billion years and will continue to do so for another 15 to 20 billion years.

4.There are about 120 globular clusters associated with our galaxy.

5a.Star clusters are important to astronomers because they use them to test their ideas of stellar evolution. They are able to do this because all the stars in the cluster are assumed to have formed at the same time.

5b.Theories of stellar evolution are based on computer models. The computer models are based on what we know about stars and the laws of physics. One of the things these models tell us is that different stars age at different rates.

5c.To test their theories, astronomers generate models of stars that would be found in a cluster. They then compare the appearance of this model cluster with observations of a real cluster. If there are significant differences, the astronomers change the model until it matches the real cluster.

M 15 INFORMATION:

1.This cluster has a slightly elliptical shape.

2.Integrated spectral type: F3

CHRISTIAAN HUYGENS
SATURN   PLANET


        Compared 
    Actual      to Earth

Distance From Sun (Average) 886 million miles 9.5 Revolution Period 29.5 years
Rotation Period 10 hr. 39 min.
Diameter Equatorial 74,900 miles 9.4 Diameter Polar 67,400 miles 8.4 Mass 95 Surface Gravity 1.16 Temperature (Cloud Tops) 180oC ( 290oF)

WHAT TO LOOK FOR THROUGH THE TELESCOPE:

1.Recommended eyepiece: 26mm or 40mm.

2.Through the telescope Saturn will appear as a yellowish ball with a ring.

3.A dark cloud feature in Saturn's atmosphere can often be seen through the telescope.

4.A dark line within the rings is called Cassini's division. It separates two of the major rings as seen from Earth. Because the rings are currently close to being edg-on, Cassini's division will probably not be visible.

5.Up to four of Saturn's moons can be seen with the telescope. The brightest of the four is Titan.

SOME "STARS" OF ASTRONOMY INFORMATION:

1.Galileo was the first to see Saturn's rings, but his telescope was too crude for him to tell what they were.

2.Christaan Huygens was the first to demonstrate (in 1656) that the rings of Saturn are in fact rings, and not some other shape.

3.He also realized that we should see the rings edge-on every 15 years (twice per Saturn's 30-year orbit). At these times, the rings seem to disappear, as they are very thin. (This will happen in 1995).

4.Huygens proposal that "Saturn is surrounded by a thin ring, not touching it anywhere" was considered to be very controversial at the time.

5.Huygens discovered Saturn's largest moon, Titan.

ADDITIONAL CHRISTAAN HUYGENS INFORMATION:

1.Born, April 14, 1629, The Hague, Netherlands. Died June 8, 1695. The well educated son of a Dutch government official.

2.Besides his observations of Saturn, Huygens is famous for ground-breaking work in optics and telescope making. His eyepiece design is still sometimes used today (much more so 20 years ago).

3.Huygens discovered the Orion Nebula in 1656. Others had noticed that the middle "star" in Orion's sword looked odd. Huygens was the first to study it with a telescope.

ADDITIONAL SATURN INFORMATION:

1.Saturn is a large ball of hydrogen and helium gas. In fact Saturn is so large for the amount of matter it contains that it would float in a bowl of water. Compare this to the moon which is a piece of rock.

2.It is difficult to see any cloud features because the cloud layers are spread out in depth. This means the lower layers are obscured by the upper ones. You should be able to see one band in the telescope.

3.If Saturn has a solid (rocky) core, it is about twice the size of the Earth.

4.Like many of the other gas planets, Saturn emits more energy than it receives from the sun.

CHRISTIAAN HUYGENS
SATURN   RINGS

GENERAL INFORMATION:

1.The rings are obvious through the telescope. Not as obvious, but often visible, is Cassini's division, a dark line within the rings.

2.From Earth three different rings can be seen. However, Voyager found that each ring is actually made up of hundreds of ringlets. The ringlets can be compared to the grooves on a phonograph album.

3.The particles in the ringlets are pieces of ice that range in size from a grain of sand up to the size of a car or house. Each of these particles orbits Saturn like a tiny moon.

4.Although the rings are 42,000 miles (67,000 km) wide they are less than 1/2 mile thick. The diameter of the rings is over 160,000 miles. Imagine that you could shrink the rings so their thickness was the same as a phonograph album. The album would be 8 tenths of a mile across.

CHRISTIAAN HUYGENS
SATURN   MOONS


Moon    Distance    Compared    Revolution  Diameter    Diameter
    from    to Earth    Period  (miles) Compared
    Saturn  /Moon           to Moon

Titan   759,000 miles   5.1 15.9 Days   3200    1.5 
Rhea    327,000 miles   2.2 4.5 Days    950 .4
Dione   234,000 miles   1.6 2.7 Days    672 1/3
Tethys  183,000 miles   1.2 45 Hours    658 1/3

GENERAL INFORMATION:

1.Saturn has at least 18 moons; four of them can ordinarily be seen with the telescope.

2a.Titan is the second largest moon in the solar system. Its 3,200 mile diameter makes it just larger than Mercury (3,029 miles) and slightly smaller than Jupiter's moon Ganymede (3,270 miles). If Titan orbited the Sun instead of Saturn, it would be called a planet.

2b.Titan Titan is unique because it is one of only two moons with an atmosphere. The atmosphere is 80% nitrogen and 20% methane with methane playing the same role on Titan as water does on Earth. That means there may be clouds of methane, lakes of methane, and ice caps of methane on Titan. Triton (Neptune's largest moon) is the other moon with an atmosphere.

Dione, Rhea Both Dione (diameter 670 miles) and Rhea (950 miles) are medium sized moons that are half ice and half rock. They are heavily cratered.
Mimas Mimas is a small moon, only 250 miles across, that has a 60 mile crater on it. The impact which formed the crater almost split the moon in two. (Mimas can't be seen through the telescope. It is only 90,000 miles from Saturn.)

5.The 18th moon of Saturn was discovered in 1990, 10 years after the last Voyager fly-by. It was discovered when astronomers went through some of the "old" Voyager photos.

EDWIN HUBBLE
M 31
SPIRAL GALAXY


Right Ascension:     0h42m01s           Best Seen:  9/1 - 2/15
Declination:        41o08'05"           Magnitude:  4.88.7
Constellation:  Andromeda


    Actual  Compared to
        Milky Way

Distance    2.2 million l.y.    --
Diameter    110-180 thousand l.y.   ~1.5
Mass    400 billion suns    --
Brightness  11 billion suns
Galactic Type   Sb  --

WHAT TO LOOK FOR THROUGH THE TELESCOPE:

1.Recommended eyepiece: 80 mm

2.When people look through the telescope they should see a fuzzy patch of light. In fact the galaxy is so large that all of it cannot fit in the field of view. This is the galaxy.

3.If they are having trouble seeing it, have them look at a star near the edge of the field, then look back to the center out of the corner of their eye.

4.The view through the telescope will not look like photographs of galaxies they may have seen. A photograph of a galaxy may have an exposure of many hours. This long exposure brings out spiral arms and other details. Our eyes allow the light to collect for only about 1/30 of a second before they refresh themselves and start over again.

SOME "STARS" OF ASTRONOMY INFORMATION:

1.Edwin Hubble first resolved the Andromeda galaxy into stars. This showed that it is, in fact, a distant galaxy of billions of stars, and not just a nearby cluster or gas cloud.

2.Hubble was able to identify Cepheid variables in M31. These stars pulsate on a regular schedule. Most importantly, there is a relation between their true brightness and the amount of time it takes them to pulsate.

3.Because the true brightness of a Cepheid can be measured simply be watching its pulsations, these stars can be used to measure distances.

4.Hubble used the Cepheids to measure the distance to M31. He showed that it is clearly farther away than the edge of our own galaxy.

5.Before Hubble's distance measurement to M31, there was no unambiguous evidence that anything was more than a few hundred thousand light years away. This laid the foundation for a picture of the universe billions of light years across.

6.Hubble didn't realize that there are actually two types of Cepheids. This mistake caused him to underestimate the distance to M31. He though it was 800,000 light years away; the correct distance is 2.2 million light years.

ADDITIONAL EDWIN HUBBLE INFORMATION:

1.Born November 20, 1889, Marshfield Missouri. Died September 28, 1953. Took his first degree in law, as a Rhodes Scholar at Oxford.

2.Did most of his work at Mt. Wilson, with the 100-inch telescope.

3.Edwin Hubble went on to show that the universe is expanding, thus setting the cornerstone for modern cosmology.

ADDITIONAL SPIRAL GALAXY INFORMATION:

1.Spiral galaxies are plate shaped with a central bulge. The whole galaxy is surrounded by an invisible spherical halo of dark matter.

2.The disk of a typical spiral galaxy is about 100,000 light years across and 2000 light years thick. The spherical central bulge is about 10,000 light years in diameter and the halo is over 100,000 light years across.

3.The average spiral galaxy contains about 100 billion stars.

4.Different generations of stars can be found in each of these three regions: second generation or newly formed stars are found in the disk; first generation or old stars are found in the halo; both generations are found in the central bulge.

5.Most of the dust and gas in the galaxy is found in the disk. Almost none is seen in the halo.

6.The spiral pattern traces the location of current star formation. It may be caused by spiral ripples in the gas of the disk or by the effects of exploding stars (supernovae) on the gas.

M 31 INFORMATION:

1.This galaxy is the famous Andromeda galaxy.

2.This galaxy is a member of the local group.

3.It is surrounded by about 140 globular clusters.

4.The nucleus rotates in about 11 million years. The outer portions of the galaxy rotate in 100 to 200 million years.

EJNAR (A-nar) HERTZSPRUNG AND HENRY NORRIS RUSSELL
h and X PERSEI
OPEN STAR CLUSTER



Right Ascension:     2h19m24s           Best Seen:  11/1 - 3/1
Declination:        57o01'27"           Magnitude:  4.4
Constellation:  Perseus


    Actual

Distance    7,400 l.y.
Diameter    70 l.y. (each)
Number of Stars few thousand 
Age     ~1 million years

WHAT TO LOOK FOR THROUGH THE TELESCOPE:

1.Recommended eyepiece: 40mm or 80mm

2.Through the large telescope only one of the clusters can be seen at a time. It will appear as a group of individual stars; much like sugar or salt sprinkled on a table top.

SOME "STARS" OF ASTRONOMY INFORMATION:

1.The stars in a cluster were all formed at about the same time out of the same cloud of gas and dust. They are have different brightnesses and temperatures, however, because they have different masses.

2.Hertzsprung and Russell were the first to make one of the most important diagrams in astronomy--now known as the Hertzsprung-Russell (or H-R) diagram. They did this work between 1905 and 1914.

3.The H-R diagram is a plot of brightness vs. temperature (or color, which is related to temperature) for a group of stars. Bright and hot stars are on the upper left of the diagram, while cool and dim ones are on the lower right. Hot, dim stars are too the lower left; cool, bright stars are to the upper right.

4.Hertzsprung and Russell showed that stars do not fall randomly on this diagram. Rather, they tend to lie only in certain areas of the graph. This is the basic observational fact that the theory of stellar evolution seeks to explain.

5.The H-R diagram is the key tool for understanding the differences between stars, and also how they evolve over time.

6.The H-R diagram for a star cluster can be used to estimate the cluster's age.

ADDITIONAL EJNAR HERTZSPRUNG INFORMATION:

1.Born Frederiksberg, Denmark, October 8, 1873. Died October 21, 1967. Educated as a chemist.

3.Hertzsprung first defined the notion of "absolute magnitude" as a standard measure of a star's true brightness (not just how bright it appears, which also depends on its distance).

4.Hertzsprung discovered the "H-R diagram" as early as 1905, well before Russell's independent discovery. But Hertzsprung published his results in an obscure journal, and Russell's results were much more detailed. Thus, both are given shared credit.

ADDITIONAL HENRY NORRIS RUSSELL INFORMATION:

1.Born October 25, 1877, Oyster Bay, New York. Died February 18, 1957. Studied at Princeton and in England.

2.Russell discovered the relationships between the colors and brightnesses of stars independently of Hertzsprung. Hertzsprung's results were published before Russell's but, Russell's were more detailed.

3.Russell made an early, unsuccesful attempt at the theory of stellar evolution. (This couldn't be done succesfully until Hans Bethe worked out the source of energy for the stars.)

4.Russell is given credit for the discovery, in 1929, that the sun is made mostly of Hydrogen. It had been previously thought that the sun's composition was similar to that of Earth.

5.Actually, Cecilia Payne-Gaposchkin had found strong evidence for the sun being mostly hydrogen several years before Russell. But Russell discouraged her from making what was, at that time, considered to be a bold claim.

ADDITIONAL OPEN CLUSTER INFORMATION:

1.They lie in the plane of the galaxy.

2.Generally they are made up of young (newly formed) stars.

3.Most open clusters will probably dissipate after a few billion years since they are loosely bound by their mutual gravity.

4.The separation of stars is about 3 light years. In the solar neighborhood stars are 4 5 light years apart.

5.They contain between 100 and 1,000 stars.

6a.Star clusters are important to astronomers because they use them to test their ideas of stellar evolution. They are able to do this because all the stars in the cluster are assumed to have formed at the same time.

6b.Theories of stellar evolution are based on computer models. The computer models are based on what we know about stars and the laws of physics. One of the things these models tell us is that different stars age at different rates.

6c.To test their theories, astronomers generate models of stars that would be the same age as the stars found in a cluster. They then compare the appearance of this model cluster with observations of a real cluster. If there are significant differences, the astronomers change the model until it matches the real cluster. In this way, they can estimate the age of the cluster.

h and X PERSI INFORMATION:

1.The cluster h (NGC 869) is the younger of the two. It is possibly one of the youngest clusters known. (Only NGC 2362 in Canis Major may be younger.)

2.X (NGC 884) may be 1,000 light years farther away and 5 million years older than h.

3.The combined mass of the clusters is about 5,000 solar masses. They have a total luminousity of 200,000 times that of the sun.

EJNAR (A-nar) HERTZSPRUNG AND HENRY NORRIS RUSSELL
M 11
OPEN STAR CLUSTER



Right Ascension:     18h49m43s          Best Seen:  7/1 - 10/15
Declination:        - 6o18'57"          Magnitude:  6.5
Constellation:   Scutum



Distance    5500 l.y.
Diameter    16 l.y.
Number of Stars more than 870
Age     500 million years

WHAT TO LOOK FOR THROUGH THE TELESCOPE:

1.Recommended eyepiece: 40mm or 80mm

2.Through the telescope the cluster will appear as a group of individual stars.

SOME "STARS" OF ASTRONOMY INFORMATION:

2.Hertzsprung and Russell were the first to make one of the most important diagrams in astronomy--now known as the Hertzsprung-Russell (or H-R) diagram.

3.The H-R diagram is a plot of brightness vs. temperature (or color, which is related to temperature) for a group of stars. Bright and hot stars are on the upper left of the diagram, while cool and dim ones are on the lower right. Hot, dim stars are to the lower left; cool, bright stars are to the upper right.

5.The H-R diagram is the key tool for understanding the differences between stars, and also how they evolve over time.

6.The H-R diagram for a star cluster can be used to estimate the cluster's age.

ADDITIONAL EJNAR HERTZSPRUNG INFORMATION:

1.Born Frederiksberg, Denmark, October 8, 1873. Died October 21, 1967. Educated as a chemist.

3.Hertzsprung first defined the notion of "absolute magnitude" as a standard measure of a stars true brightness (not just how bright it appears, which also depends on its distance).

ADDITIONAL HENRY NORRIS RUSSELL INFORMATION:

1.Born October 25, 1877, Oyster Bay, New York. Died February 18, 1957. Studied at Princeton and in England.

3.Russell made an early, unsuccesful attempt at the theory of stellar evolution. (This couldn't be done succesfully until Hans Bethe worked out the source of energy for the stars.)

4.Russell is given credit for the discovery, in 1929, that the sun is made mostly of Hydrogen. It had been previously thought that the sun's composition was similar to that of Earth.

ADDITIONAL OPEN CLUSTER INFORMATION:

1.They lie in the plane of the galaxy.

2.Generally they are made up of young (newly formed) stars.

3.Most open clusters will probably dissipate after a few billion years since they are loosely bound by their mutual gravity.

4.The separation of stars is about 3 light years. In the solar neighborhood stars are 4 5 light years apart.

5.They contain between 100 and 1,000 stars.

M 11 INFORMATION:

1.Most of the brightest main sequence stars are of spectral type A and F.

2.It also has about 500 stars which are brighter than 14th magnitude.

3.The average separation of the stars in the cluster is about 1 light year.

4.All of the bright stars in this cluster are very luminous giants.

5.The total brightness of the cluster is about 10,000 times the brightness of the sun.

WILLIAM AND CAROLYN HERSCHEL
DUMBBELL NEBULA (M27)
PLANETARY NEBULA



Right Ascension:    19h58m28s           Best Seen:  7/1 - 11/15
Declination:        22o39'02"           Magnitude:  8.0
Constellation:  Vulpecula


    Actual  Compared to

Distance    900 l.y.    --
Diameter    2.5 l.y.    150,000 (Earth-Sun)
Actual Brightness (of central star) --  .5 (Sun)
Magnitude of central star:  13.5    --
Spectral Type of Central Star   --  --
Surface Temperature of Star 85,000oK    --
Age     48,000 years    --

WHAT TO LOOK FOR THROUGH THE TELESCOPE:

1.Recommended eyepiece: 26mm or 40mm

2.This object will look like a whitish, hazy cloud when seen through the telescope.

SOME "STARS" OF ASTRONOMY INFORMATION:

1.William Herschel first coined the term "planetary nebula", and first recognized them as being a distinct type of celestial object.

2.William and Carolyn Herschel (brother and sister), in the course of a general survey of the night sky, discovered many small, round, relatively bright nebulae.
3.Through a telescope, many of the planetary nebulae appear similar to a telescopic view of Uranus. Thus, the name. They have nothing physically to do with planets at all.

4.A planetary nebula is a shell of glowing gas around an aging, low-mass star. But the Herschels had no way of knowing this.

5.William Herschel, at different times during his life, thought the planetary nebulae were glowing clouds of gas (right) or unresolved clusters of stars (wrong).

6.The Herschels misidentified many small bright galaxies as being planetary nebulae. They also failed to include some of the larger planetary nebulae in their list.

ADDITIONAL WILLIAM HERSCHEL INFORMATION:

1.Born November 15, 1738, Hanover, Germany. Died August 25, 1822. Born into a family of musicians, in war-torn Germany. Emigrated to England at the age of nineteen.

2.William Herschel was a succesful musician in Bath, England, when he began to take up astronomy seriously. He eventually abandoned music altogether.

3.Herschel can be considered the founder of much of the astronomy that followed after him:

Pioneered the use and construction of large, reflecting telescopes.
Discovered that binary stars orbit about each other.
Discovered the planet Uranus.
First showed the motion of the solar system relative to nearby stars.
First to use statistics in astronomy
With his sister, made the first comprehensive survey of "deep-sky" objects
First to attempt to determine the shape of our Galaxy.
Discovered infrared light

4.William Herschel had a brash, amateurish style, but with a keen eye for where the heart of the problem lay. This was exactly what was needed at the time he came along. Astronomy was in something of a rut--with very detailed, rigorous answers being found for not-very-interesting questions. Herschel's main genius lay in asking many important questions that had been hitherto ignored, and then finding clever ways to get at least rough answers.

ADDITIONAL CAROLYN HERSCHEL INFORMATION:

1.Born 1750, in Hanover, Germany. Died in 1848.

2.Carolyn Herschel was William's sister, and his assistant throughout his life. She emigrated to England in her early 20s, originally to be a singer. She had already established a succesful career as a soprano when her brother decided he wanted to be a full-time astronomer. Carolyn was initially not at all happy about giving up her singing career to be an assistant astronomer. But she soon came to love astronomy, and continued to do so decades after her brother's death.

3.Carolyn acted as her brother's assistant in virtually all of his astronomical work (and much of his musical work as well). She helped make the telescopes, assisted in the observations, and then reduced the data and prepared the manuscripts for publication.

4.The observational data for the Herschels' monumental survey of the heavens was reduced by Carolyn (a task which involved mountains of calculations) after William died in 1822. It was never published, but it served as the foundation for the New General Catalog (NGC) published some 70 years later. We still use the NGC today.

5.In her spare time (of which there was little), Carolyn became an accomplished observer in her own right. She was the first woman to discover a comet, and she discovered a total of 8 in 11 years.

ADDITIONAL PLANETARY NEBULA INFORMATION:

1.As stars begin to die, they expand to become red giants. The sun will begin this process in 4 5 billion years. When the sun becomes a red giant the Earth's atmosphere and oceans will be evaporated into space. In fact, there is a chance that the whole Earth might evaporate.

2.At the end of the red giant phase, the star gently puffs off its outer layers. This forms the planetary nebula.

3.The gas moves away from the star with speeds of 6 20 miles per second (10 to 30 km/sec). After 50 100 thousand years, the shell of gas has moved far enough from the star so it no longer shines.

4.Only about 10% of the star is puffed off. The rest of the star shrinks until it is about the size of the Earth. This star is called a white dwarf.

5.White dwarfs are no longer generating any energy so they will cool off and eventually become black.

6.White dwarfs contain as much matter as the sun but are Earth sized. One teaspoon of white dwarf star stuff brought to Earth would weigh as much as a loaded semitrailer or 1½ African elephants.

7.The sun will become a white dwarf in about 5 billion years.

8.There are probably between 20 and 50 thousand planetary nebulae in our galaxy.

DUMBBELL NEBULA INFORMATION:

1.The nebula is expanding at 17 miles per second.

2.This planetary's age of 48,000 years makes it about 2.5 times older than the average age (20,000 years) of typical bright planetary nebulae.

3.The central star's temperature of 85,000oK, makes it one of the hottest stars known.

4.The central star may be a double star with a separation of 1.6 trillion miles (.28 light years or 18,000 times the Earth-sun distance).

WILLIAM AND CAROLYN HERSCHEL
NGC 7662
PLANETARY NEBULA



Right Ascension:    23h25m54s           Best Seen:  7/1 - 11/15
Declination:        42o33'          Magnitude:  9.2
Constellation:  Andromeda


    Actual  Compared to

Distance    5600 l.y.   --
Diameter    0.8 l.y.    50,000 (Earth-Sun)
Actual Brightness (of central star) --  .5 (Sun)
Magnitude of central star:  12-16   --
Spectral Type of Central Star   --  --
Surface Temperature of Star 85,000oK    --
Age     48,000 years    --

WHAT TO LOOK FOR THROUGH THE TELESCOPE:

1.Recommended eyepiece: 26mm or 40mm

2.This object will look like a small bluish ball in the telescope. It may appear ring-shaped at higher magnification.

SOME "STARS" OF ASTRONOMY INFORMATION:

1.William Herschel first coined the term "planetary nebula", and first recognized them as being a distinct type of celestial object.

4.A planetary nebula is a shell of glowing gas around an aging, low-mass star. But the Herschels had no way of knowing this.

5.William Herschel, at different times during his life, thought the planetary nebulae were glowing clouds of gas (right) or unresolved clusters of stars (wrong).

6.The Herschels misidentified many small bright galaxies as being planetary nebulae. They also failed to include some of the larger planetary nebulae in their list.

7.NGC 7662 is number 18 in the Herschels' list of planetary nebulae.

ADDITIONAL WILLIAM HERSCHEL INFORMATION:

1.Born November 15, 1738, Hanover, Germany. Died August 25, 1822. Born into a family of musicians, in war-torn Germany. Emigrated to England at the age of nineteen.

2.William Herschel was a succesful musician in Bath, England, when he began to take up astronomy seriously. He eventually abandoned music altogether.

3.Herschel can be considered the founder of much of the astronomy that followed after him:

Pioneered the use and construction of large, reflecting telescopes.
Discovered that binary stars orbit about each other.
Discovered the planet Uranus.
First showed the motion of the solar system relative to nearby stars.
First to use statistics in astronomy
With his sister, made the first comprehensive survey of "deep-sky" objects
First to attempt to determine the shape of our Galaxy.
Discovered infrared light

ADDITIONAL CAROLYN HERSCHEL INFORMATION:

1.Born 1750, in Hanover, Germany. Died in 1848.

5.In her spare time (of which there was little), Carolyn became an accomplished observer in her own right. She was the first woman to discover a comet, and she discovered a total of 8 in 11 years.

ADDITIONAL PLANETARY NEBULA INFORMATION:

2.At the end of the red giant phase, the star gently puffs off its outer layers. This forms the planetary nebula.

3.The gas moves away from the star with speeds of 6 20 miles per second (10 to 30 km/sec). After 50 100 thousand years, the shell of gas has moved far enough from the star so it no longer shines.

4.Only about 10% of the star is puffed off. The rest of the star shrinks until it is about the size of the Earth. This star is called a white dwarf.

5.White dwarfs are no longer generating any energy so they will cool off and eventually become black.

6.White dwarfs contain as much matter as the sun but are Earth sized. One teaspoon of white dwarf star stuff brought to Earth would weigh as much as a loaded semitrailer or 1½ African elephants.

7.The sun will become a white dwarf in about 5 billion years.

8.There are probably between 20 and 50 thousand planetary nebulae in our galaxy.

NGC 7662 INFORMATION:

1.The central star's temperature of 75,000oK, makes it one of the hottest stars known.

HANS BETHE (pronounced like beta)
BETA CYGNI
CONTRAST BINARY (DOUBLE) STAR


Right Ascension:    19h29m43s           Best Seen:  6/15 - 11/15
Declination:        27o54'28"           Magnitude:  3.09
Constellation:  Cygnus          Apparent Separation: 34.3"


    Actual  Compared to

Distance    410 l.y.    --
Separation  440 billion miles   4400 Earth/Sun
Actual Brightness   --  760 / 120 (Sun)
Magnitude:  3.09 / 5.11 --
Spectral Type   K3 III / B8 V   --

WHAT TO LOOK FOR THROUGH THE TELESCOPE:

1.Recommended eyepiece: 24mm or 40mm

2.When people look through the telescope they should see two stars next to each other. The brighter star should appear yellow and the dimmer star blue.

SOME "STARS" OF ASTRONOMY INFORMATION:

1.The two stars are different colors because they are different temperatures.

2.The central temperature of a star must be extrememly high in order to keep it from being crushed by gravity. Also, a star can last for billions of years, so it must have a very efficient energy source to keep it so hot for so long.

3.In the late 1930's, Hans Bethe first worked out the details of how a star generates so much energy.

4.Bethe showed exactly how a star can be powered by hydrogen fusion. Four hydrogen atoms fuse into one helium atom. In the process, a tiny bit of the mass is converted to energy.

5.There are actually two different ways hydrogen can fuse into helium. The "proton-proton cycle" works in low mass stars (like the sun), while the "CNO cycle" works in high mass stars. Hans Bethe figured out both reaction paths.

ADDITIONAL HANS BETHE INFORMATION:

1.Born July 2, 1906, in Strassburg, Germany. Studied in Munich, Cambridge, and Rome. When Hitler came to power in 1933, Bethe left Germany, teaching in England until 1935. He then accepted a post at Cornell University in the U.S., where he is now professor emeritus.

2.Bethe served as the director of the Theoretical Physics Division at Los Alamos during the Manhattan Project.

3.For his work on thermonuclear reactions in the sun, Bethe won the Nobel Prize in 1967.

4.When Bethe completed his work on hydrogen fusion in stars, he delayed publication so he could enter the research in a contest. He won, and then used the prize money to help his mother emigrate from Nazi Germany. "The Nazis were quite willing to let my mother out, but they wanted $250.00, in dollars, to release her furniture. Part of the prize money went to liberate my mother's furniture."

ADDITIONAL CONTRAST BINARY STAR INFORMATION:

1.A double star is simply two stars that revolve around each other much like the Earth orbits the sun.

2.This double star is special because you can see two different colors. The red or yellow star is cooler than the blue star.

3.Often the cooler star will be brighter than the hotter star. This can lead into a discussion on how the sizes of stars, along with their temperatures, affect how bright they are.

4.Over half of the stars in the sky are double or multiple star systems. They can't be seen as individual stars because they are too far away and too close together. A good analogy is the headlights of a distant car.

5.At least one multiple star system has as many as 9 components.

6.Note that the sun is just an ordinary star.

BETA CYGNI INFORMATION:

1.This star is also known as Albireo. It is one of the best known contrast binary star systems.

2.About 60 of our solar systems could be laid edge to edge between these two stars.

HANS BETHE (pronounced like beta)
GAMMA ANDROMEDA
CONTRAST BINARY (DOUBLE) STAR


Right Ascension:     2h02m21s           Best Seen:  10/15 - 3/15
Declination:        42o12'35"           Magnitude:  2.12
Constellation:  Andromeda           Apparent Separation: 10"


    Actual  Compared to

Distance    260 l.y.    --
Separation  74 billion miles    800 Earth/Sun
Actual Brightness   --  650 / 50 (Sun)
Magnitude:  2.1 / 5.5   --
Spectral Type   K2 II / B9  --

WHAT TO LOOK FOR THROUGH THE TELESCOPE:

1.Recommended eyepiece: 24mm or 40mm

2.When people look through the telescope they should see two stars next to each other. The brighter star should appear yellow and the dimmer star blue.

SOME "STARS" OF ASTRONOMY INFORMATION:

1.The two stars are different colors because they have different surface temperatures.

3.Hans Bethe first worked out the details of how a star generates so much energy.

4.Bethe showed exactly how a star can be powered by hydrogen fusion. Four hydrogen atoms fuse into one helium atom. In the process, a tiny bit of the mass is converted to energy.

ADDITIONAL HANS BETHE INFORMATION:

2.Bethe served as the director of the Theoretical Physics Division at Los Alamos during the Manhattan Project.

3.For his work on thermonuclear reactions in the sun, Bethe won the Nobel Prize in 1967.

ADDITIONAL CONTRAST BINARY STAR INFORMATION:

1.A double star is simply two stars that revolve around each other much like the Earth orbits the sun.

2.This double star is special because you can see two different colors. The red or yellow star is cooler than the blue star.

3.Often the cooler star will be brighter than the hotter star. This can lead into a discussion on how the sizes of stars, along with their temperatures, affect how bright they are.

5.At least one multiple star system has as many as 9 components.

6.Note that the sun is just an ordinary star.

GAMMA ANDROMEDA INFORMATION:

1a.The blue star is really a triple star system (stars B, C, and D). Stars C and D revolve around each other and then the pair and B revolve around each other.

1b.Stars C and D are a spectroscopic binary system with a period of 2.67 days.

1c.Stars B and the C/D pair are separated by a bit less than 3 billion miles (30 times the Earth/Sun distance). The orbital period of this system (B and C/D) is 61 years.

2.Note that the colors of these stars may be more striking if they are slightly out of focus.

JEAN BERNARD LEON FOUCAULT (foo-COE)
ROTATION OF THE EARTH


Right Ascension:    
Declination:            
Constellation:

WHAT TO LOOK FOR THROUGH THE TELESCOPE:

1.Recommended eyepiece: 40mm

2.Enter the command "foucault." This command will automatically slew the telescope to the proper coordinates and then shut off the tracking. When you are ready to move to the next object, you must type in "starrate."

3.With the tracking off, the rotation of the Earth will be apparent as the stars drift across the field of view in the eyepiece. A given star will drift clear across the field of view in about 1 minute. The motion should be apparent after viewing for 10 seconds or so.

SOME "STARS" OF ASTRONOMY INFORMATION:

1.As Earth turns, the whole sky appears to rotate over our heads. This is because we point toward different points in space as we are carrried around by the turning Earth.

2.But how do we know that Earth is actually turning? Maybe the whole universe turns around Earth once a day! How do we know we're doing the moving?

3.Foucault was the first to demonstrate conclusively that Earth really (and truly) does rotate (although no one had really doubted this fact at least since the time of Galileo). He demonstrated this with the famed Foucault Pendulum.

2.A pendulum will try to swing always in the same plane (because of the conservation of angular momentum), even if it is being carried along with the rotating Earth's surface.

3.As seen from the surface of Earth then, the pendulum appears to slowly change the direction of its swing as Earth turns. This was first publicly demonstrated by Foucault in 1851.

ADDITIONAL JEAN FOUCAULT INFORMATION:

1.Born September 19, 1819, in Paris. He was a shy, frail bookseller's son. Originally studied medicine. Died 1868.

2.Besides his famous pendulum, Foucault made several key innovations in telescope making. Previously, mirrors for reflectors were made out of metal. Foucault perfected the method of putting a coating of silver on glass. He also devised a method to accurately monitor the exact shape of a telescope mirror as it is being polished. This method is now known as the Foucault Test.

3.Foucault, along with his friend Fizeau, made pioneering measurements of the speed of light. In particular, he first showed that light travels more slowly through water than through air. This demonstrated that the light was acting as a wave, rather than as a stream of particles.

ADDITIONAL EARTH'S ROTATION INFORMATION:

1.Earth rotates 360 degrees, one full rotation, once every 23 hours, 56 minutes. Our clock day is 4 minutes longer than this because we reckon our time with the sun. Since we are also orbiting around the sun, Earth has to rotate an additional 1 degree to point back at the sun, which is no longer quite in the same direction as it was the day before. It takes about 4 minutes for Earth to rotate this extra 1 degree.

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