Dance Across the Night Sky with Cassiopeia the Queen
Posted: October 24, 2010 Filed under: Alpha Cassiopeiae, American Astronomical Society, astronomers, Astronomical Societies, astronomy, astronomy equipment, Beta Cassiopeiae, binoculars, Charles Messier, constellations, entertainment, Gamma Cassiopeiae, John Hopkins University, M 103, M 52, Messier catalogue, NASA, National Solar Observatory, New General Catalogue, October 2010, Ptolemy, Royal Astronomical Society, spiral galaxies, telescope accessories, telescopes, the Milky Way galaxy, the Universe | Tags: Alpha Cassiopeiae, Beta Cassiopeiae, Cassiopeia the Queen, constellations in the northern sky, constellations viewable in autumn's northern sky, Gamma Cassiopeiae, Halloween star treats, Journey to the Beginning of Space and Time, M 103, M52, NGC 129, NGC 581, NGC 7654, Ptolemy, time machine to the stars 2 Comments »
This star map gives you an idea of the stars in and around Cassiopeia the Queen
Cassiopeia the Queen is one of the first northern deep sky objects we’ll view during our “Journey to the Beginning of Space and Time”. Cassiopeia the Queen is easily recognizable in autumn’s night sky using her characteristic W or M shape form and she was one of the 48 constellations originally listed by the 2nd century Greek astronomer Ptolemy during his observations of the night sky. Today, Cassiopeia the Queen is one of 88 constellations recognized by modern star gazers in the night sky, and the abundance of magnificent open star clusters within her arms provides viewers with a chance to see a variety of outstanding celestial objects that have been entertaining star gazers for thousands of years.
Five stars outline Cassiopeia's characteristic W shape
Cassiopeia the Queen is a familiar sight for modern astronomers and star gazers in the mid-northern latitudes of planet Earth, and is often one of the first constellations in the northern sky beginning star gazers journey to view. Board your time-machine-to-the-stars near the end of October, or the beginning of November, and take the family on a journey through time and space to visit Cassiopeia the Queen. A visit with Cassiopeia the Queen will open a child’s mind to the possibilities of the universe, before them, and your wife will be able to tell her friends that you took her out last night.
8x50 astronomical binoculars will reveal about 12 stars nestled in among the collective glow of other stars to faint to resolve
One of the best open star clusters you can view with the naked eye is 6.5 magnitude NGC 129, a large, bright, open cluster of stars 8×50 astronomical binoculars will reveal to have six to twelve brighter stars nestled within the collective glow of a field of stars to faint to resolve using binoculars. You should see about 35 celestial bodies in this region of space and time 5,200 light years distant from your position on the Earth. Look toward the north of two 9th magnitude stars, near the center of NGC 129, and you’ll find the Cepheid variable DL Cassiopeiae. DL Cassiopeiae will fluctuate between 8.6 and 9.3 magnitude, over the course of an eight-day cycle.
The central star in Cassiopeia’s characteristic W is Gamma Cassiopeiae, a prototype for a class of irregular variable stars believed to be rapidly spinning type-B celestial bodies often fluctuating by as much as magnitude 1.5 or more, Gamma Cassiopeiae will flicker between 2.2 and 3.4 magnitude as you watch her nightly dance and this star at maximum brightness outshines both Alpha Cassiopeiae and Beta Cassiopeiae. Astronomers believe these apparent fluctuations are due to a decretion disc around this star resulting from the rapid spinning of the star, which results in some of the star’s mass forming a decretion disc. Gamma Cassiopeiae is also a spectroscopic binary star with an orbital period of about 204 days and astronomers believe Gamma Cassiopeiae’s companion star is about the same relative mass as Sol. Part of a small group of stellar sources in the night sky that beam of X-ray radiation about 10 times higher than the X-rays emitted from other type-B stars across the cosmos, Gamma Cassiopeiae exhibits both short-term and long-term cycles of x-ray emission. Star gazers should also be able to view Gamma Cassiopeiae as an optical double star, with a faint magnitude 11 companion star, about 2 arc seconds distant from Gamma Cassiopeiae.
Ancient star gazers in China called Gamma Cassiopeiae Tsih, which loosely translates as “the whip”, but no references have been found in Arabic or Latin texts of Gamma Cassiopeiae being referred too using a different name. Modern star gazers refer to Gamma Cassiopeiae by a number of different designations, including 27 Cassiopeiae, HR 264, HD 5394, and others. Modern astronauts often use Gamma Cassiopeiae as a star-guide because it’s a relatively bright celestial object and in previous space missions this star was used as an easily recognizable navigational reference point in the night sky.
M103 (NGC 581) will reveal about 25 magnitude 10 or fainter stars
M103 (NGC 581) is the first of two Messier objects in Cassiopeia’s arms viewable through a six-inch time-machine-to-the-stars and should appear as about three dozen stars grouped in a triangular area 6′ across. A fairly compact open cluster, M103 will be 1 degree east of Delta Cassiopeiae, and is the left bottom star of Cassiopeia’s characteristic W shape marking her throne in the night sky. Pierre Mechain was first given credit for seeing this open cluster in the night sky in 1781. Star gazers using 8×50 binoculars will see about 25 magnitude 10 or fainter stars in their view and a string of four stars immediately to M103′s southeast, which adds to the beauty of viewing M103, significantly.
M 52 (NGC7654) is one of the richest open clusters to view north of the celestial equator
The second Messier object in Cassiopeia catalogued by Messier is M52 (NGC 7654), you can locate M52 by drawing a line from Alpha Cassiopeiae through Beta Cassiopeiae, and then extending your line an equal distance to M52. An 8-inch time-machine-to-the-stars will reveal about 75 stars in the night sky clumped in various patterns along the edge of the Milky Way that aren’t lost among the background points of light behind these stars. One of the richest open clusters in Cassiopeia’s arms and north of the celestial equator, Messier made note of M52 in his catalogue in 1774. This open cluster will appear as a nebulous mass of about 100 stars in 8×50 astronomical binoculars, with a few individual stars that you can resolve a little better. Star gazers looking for a little extra should look to the north of M52 to find Harrington 12, a wide triangular looking asterism containing about a dozen 5th to 9th magnitude stars, which will appear spectacular in low-power astronomical binoculars.
Journey less than 3 degrees south of Delta Cassiopeiae to find the spectacular Owl Cluster (NGC 457), a celestial object ancient star gazers could plainly see in the north night sky, the Owl Cluster’s wings will be clearly viewable using a 4-inch time-machine-to-the-stars. Star gazers can also locate Delta Cassiopeiae by using 5th magnitude Phi Cassiopeiae and 7th magnitude HD 7902, which lie to the southeast of the Owl Cluster. The Own’s eastern wing is a line of four bright stars, while the western wing is composed of two pairs of stars arranged in a long rectangle. The brightest star in the Owl Cluster will shine at 8.6 magnitude and will appear a little orange in color in star gazers.
Cassiopeia the Queen reigns in autumn's night sky
Navigating the Universe Using the Stars as Your Guide
Posted: October 23, 2010 Filed under: altitude-azimuth coordinate system, American Astronomical Society, astronomers, Astronomical Societies, astronomy, Earth, entertainment, equatorial coordinate system, Goddard Flight Center, International Astronomical Union, John Hopkins University, NASA, National Solar Observatory, Royal Astronomical Society, sky coordinate systems, space history, star catalogues, the day and night cycle of Earth, The Earth, the Earth's orbit, the Earth's rotation, the months | Tags: altitude-azimuth coordinate system, astronomers, astronomy, azimuth, Big Dipper, Celestial cartographers, celestial equator, celestial globes, celestial sphere, declination, equatorial coordinate system, Journey to the Beginning of Space and Time, night sky, right ascension, star gazers, zenith 1 Comment »Astronomers use coordinate systems to plot the position of stars in the night sky
Looking up into the night sky you probably wonder how ancient star gazers were able to navigate using the stars in the night sky as their guide. One of the first things ancient star gazers did to help them navigate the night sky, and the surface of the Earth, was to create a coordinate system to pinpoint relative positions of the stars in the night sky in relation to one another.
Looking upward into the night sky, imagine the sky above you as a sphere of infinite size, centered on the Earth. This technique works in general because distances to the stars above you is not discernible using your naked eye, so the objects you see above you in the night sky all appear to lie on a great sphere at an infinite distance in relation to you.
Modern astronomers use two coordinate systems to determine the relative positions of objects in the night sky; the altitude-azimuth coordinate system and the equatorial coordinate system. We will talk a little about both coordinate systems currently being used by modern astronomers to help them plot the positions of the objects they view in the night sky and using celestial objects you view on your “Journey to the Beginning of Space and Time” to navigate your way through the universe.
The altitude-azimuth system works fine
In the altitude-azimuth coordinate system altitude indicates the number of degrees from the horizon to the object in the night sky you’re viewing, and ranges from 0 degrees at the horizon to 90 degrees at the zenith above you. Modern astronomers measure azimuth along the horizon from north to east, to the point where a line passing through the object in the night sky intersects the horizon at a right angle, and azimuth varies between 0 degrees and 360 degrees. Astronomers also subdivide each degree of azimuth into 60 arcminutes and each archminute into 60 arcseconds, which helps to further subdivide the immense distances between each degree of measurement in the night sky.
Navigating the night sky becomes a lot easier using a coordinate system
The altitude-azimuth coordinate system doesn’t take into account the rotation of the Earth, though, and astronomers have solved this problem by fixing coordinates to the celestial sphere you imagine above you in the night sky. Celestial cartographers have created “celestial globes”, similar to the globes of the Earth that cartographers have devised for centuries to show the Earth and all of its features. On these celestial globes you’ll find terms like the celestial equator and North and South celestial poles.
The equatorial coordinate system works even better for navigating the night sky
In the equatorial coordinate system astronomers use two aspects called declination and right ascension to fix a star’s position on the celestial sphere you picture above you. Declination is analogous to Earth’s latitude and represents the angle between the object you’re viewing in the night sky above you and the celestial equator. Declination varies between 0-90 degrees, North and South of the celestial equator, and is measured in degrees, arcminutes, and arcseconds, while a minus sign is used to designate objects south of the celestial equator.
The equatorial system is more widely used today
The lines of circles that run through the celestial poles perpendicular to the celestial equator represent the hour circle of objects in the night sky above your head, and are analogous to the meridian of longitude on the Earth. In order to fix an objects position in the celestial sphere above you we’ll also need to set the zero point of the longitude coordinate of the object, which astronomers call the objects right ascension. In order to accomplish this we need an intersection point between the Earth’s equator and its orbital plane, the elliptic. Astronomers call this intersection point the vernal equinox and the sun appears to travel through the intersection point annually around March 21, as it moves South to North crossing the celestial equator.
The angle that lies between the vernal equinox and the point where the hour circle of the celestial object in question intersects the celestial equator is the right ascension of the object you see in the night sky. Right ascension is measured in hours (h), minutes (m), and seconds (s), from west to east, and the vernal equinox is zero-hour. There are about 24 hours in each day on the Earth, so each hour of right ascension in the night sky corresponds to 15 degrees of longitude.
The movement of the Earth and the objects in the night sky above you mean the appearance of the night sky is dynamic in nature, so celestial objects will appear to circle the celestial poles as you watch the night sky. A star with a greater distance from a celestial pole than your latitude will only be visible to you during a portion of its orbit. In this case the star will rise in the east and set in the west. Stars that are always above your horizon are circumpolar for your latitude and you’ll see these stars for their entire orbit.
The Earth’s rotation and the movement of the stars also means the constellations in the night sky above you travel slowly westward during the year. Pinpoint a star you know well in the night sky at exactly 9 P.M. tonight. This same star will be in the exact same position in the night sky tomorrow night, only 4 minutes earlier, at 8:56 P.M. Check the time this same star is in the same position on the next night and you’ll see this occurs at 8:52 P.M.
Do a little math and you’ll verify that in one month this set up would leave the stars in the night sky 2 hours out of phase with our first positional reading in the night sky for this same star. In 3 months, generally one season, the stars in the night sky above you will have traveled a quarter of the way across the night sky. After four seasons, this would bring the star in question back to the same position in the night sky as twelve months before.
One way to estimate distances in the night sky above you and give yourself a tool to help you navigate the universe on your “Journey to the Beginning of Space and Time” is to use star pairs in the night sky as your guide. Star travelers can learn by using star pairs in the Big Dipper, for example.
On a star atlas you’ll see objects on the map described as 12 degrees from such-and-such a star. If you study the separations between the stars of well-known stars, like the ones in the Big Dipper, you can train your eyes to visually estimate distances between stars. Take a look at a star chart of the Big Dipper and you’ll see that Alpha Ursae Majoris is about 5 degrees separated from Beta Ursae Majoris. Delta Ursae Majoris, on the other hand, is 10 degrees from Beta Ursae Majoris, while Beta Ursae Majoris is about 25 degrees from Eta, and this trend continues. Star gazers can learn to visually estimate graduations less than 1 degree in the night sky as well. Use the Full Moon, which measures 1/2 degree across. This distance is close to the distance between two stars in Scorpio’s stringer and if you use it as your measuring stick, you’ll see other pairs with about the same separation in the night sky above you. Search the night sky as you “Journey to the Beginning of Space and Time” for road markers and celestial objects you can use to navigate your way to infinity. This will help you find your way back from your trip and navigate the night sky to the objects you want to view.
Millions of Light-Years and Infinity Inbetween
Posted: October 18, 2010 Filed under: astronomers, astronomy, Charles Messier, Gerald de Vaucouleurs, John Herschel, Messier catalogue, star catalogues, star evolution, Ursa Major North Group, Ursa Major South Group, Virgo supercluster, William Herschel | Tags: astronomers, astronomy, Charles Messier, Coma Berenices, Gerard de Vaucouleurs, John Herschel, Journey to the Beginning of Space and Time, Local Group of galaxies to Milky Way, Messier catalogue, Messier objects, Milky Way, time machine to the stars, Ursa Major North Group, Ursa Major South Group, Virgo, Virgo supercluster, William Herschel Leave a comment »
Our Local Group of galaxies
Look upward at the night sky and you’re viewing the stars of the Milky Way galaxy as they were hundreds and even thousands of light-years in the past. The time it takes the starlight from these celestial bodies to travel the distance between these stars and Earth is very long in human terms, despite the speed of light. If astronomers indicate that a particular galaxy is sixty-million light-years away from Earth, this means it takes light sixty-million light-years to travel the distance to Earth from this galaxy. The true environments existing in distant galaxies remains a mystery for the moment. We’ll board our time-machine-to-the-stars tonight and “Journey to the Beginning of Space and Time’ to take a look a look at the local group of galaxies within the gigantic wheel of the Virgo Supercluster. The physical reality existing in these distant galaxies is likely to be unlike anything imaginable by humankind and things out among distant galaxies doesn’t work as you have been taught things work on Earth. Travelers unfamiliar with Einstein’s relativity need to bone-up on special and general relativity, before getting on board, this will help you deal with the realities of your “Journey to the Beginning of Space and Time”.
Astronomers looking upward into the night sky realised centuries ago that deep-sky objects are distributed unevenly about the night sky. French comet hunter Charles Messier (1730-1817) looking upward into the night sky through his time-machine-to-the-stars compiled a popular catalog of deep-sky objects. His catalogue contains high concentrations of deep-sky objects within the Milky Way above you, where open star clusters and star-forming areas that form them congregate.
Messier’s catalogue also contains entries on 16 objects he located near the border between the constellations Virgo and Coma Berenices. Star gazer William Herschel (1738-1822) and his son, John Herschel (1792-1871), recorded more than 200 celestial objects in this same region of the night sky. It would be in the 1920s and 1930s that astronomers would determine that these nebulous objects are in fact galaxies as big, or larger than, the Milky Way galaxy that constitute a cluster of galaxies far beyond the Milky Way.
Two decades later, French-born astronomer Gerard de Vaucouleurs (1918-1995) noted that the halo of galaxies surrounding what astronomers referred too as the Virgo cluster actually extends all the way to our Local Group of galaxies, which the Milky Way calls home. Today astronomers refer to this Local Group of galaxies as our Local Supercluster of galaxies.
Presently, astronomers believe our Local Supercluster extends 50 million light-years, from the center of the Virgo cluster. We’ll journey from the center of our Local Group to slightly beyond the Virgo cluster. Along the way we’ll stop at all of the galaxy groups and clusters containing at least three reasonably large galaxies and see what astronomers have determined about these distant celestial bodies in the night sky above you.
The first celestial object in the night sky we’ll journey to see is called the Ursa Major North Group, next we’ll travel to Ursa Major South Group, and then make our way to each of the galaxy groups and clusters in the Milky Way’s Local Group of neighbors.
The Virgo cluster is mostly empty space, with dense areas of matter in between
A Greek Letter for Every Star
Posted: October 11, 2010 Filed under: American Astronomical Society, astronomers, Astronomical Societies, astronomy, entertainment, Goddard Flight Center, International Astronomical Union, Johannes Bayer, John Hopkins University, NASA, National Solar Observatory, Royal Astronomical Society, star catalogues | Tags: astronomers, astronomy, Atlas of the Constellations, Big Dipper, Greek alphabet, Johannes Bayer, naming stars, science, space, star charts, star designations, star maps, star names Leave a comment »Star maps and the Greek alphabet
Anybody understand Greek?
The names and designations of the stars and celestial bodies in the night sky above your head were first officially documented around 1603. In this year, German map maker Johannes Bayer published his “Atlas of the Constellations”, in which he plotted the positions in the night sky of more than 2,000 celestial objects. Previous star charts in contrast designated stars according to their position within the mythological figures of constellations in the night sky.
Bayer’s Uranometria star classification system uses Greek letters to differentiate the varying brightness of stars in the night sky. Using Bayer’s system Alpha is normally used to designate a constellation’s brightest star, Beta to designate the second brightest in a constellation, and this trend continues through the Greek alphabet. Bayer would sometimes letter stars in a constellation sequentially as well and under this system the stars of the Big Dipper, for example, are designed Alpha, Beta, Gamma, Delta, Epsilon, Zeta, and Eta.
Modern astronomers have made their own additions and tweaks to the star classification system in use today. Celestial Cartographers studying the night sky now use numbered characters as designators for stars and celestial objects in the night sky. They haven’t added any new Greek letters to the constellations in the night sky, so look for the greek letters listed below on star maps of the constellations in the night sky, and this will provide you with stars you can use as road markers on your “Journey to the Beginning of Space and Time”.
Alpha
Beta
Gamma
Delta
Epsilon
Zeta
Eta
Theta
Iota
Kappa
Lambda
Mu
Nu
Xi
Omicron
Pi
Rho
Sigma
Tau
Upsilon
Phi
Chi
Psi
Omega
Good old English! It's in English, right?
A Star Catalogue for Every Age and Star Gazer
Posted: October 10, 2010 Filed under: American Astronomical Society, astronomers, Astronomical Societies, astronomy, entertainment, Goddard Flight Center, International Astronomical Union, John Hopkins University, NASA, National Solar Observatory, New General Catalogue, Royal Astronomical Society, star catalogues, the Universe | Tags: Andromeda Galaxy (NGC 224), astronomers, astronomy, John L. E. Dreyer, M31, M42, M57, New General Catalogue, NGC 7789 in Cassiopeia, star catalogues, star guides, the Orion Nebula (NGC 1976), the Ring Nebula (NGC 6720) 1 Comment »Valuable star-guides for your “Journey to the Beginning of Space and Time”
Red and Orange Fills September’s Night Sky
Posted: September 17, 2010 Filed under: astronomers, astronomy, entertainment, Hans Schjellerup, John Birmingham, NASA, September 2010, spiral galaxies, star catalogues, the Milky Way galaxy, The Red Region, The Red Stars: Observations and Catalogue, the Universe | Tags: Aquila, astronomers, binoculars, Cygnus, double star Albireo, Earth, Hans Schjellerup, John Birmingham, Journey to the Beginning of Space and Time, Lyra, Milky Way Galaxy, Mother Nature, news, night sky, science, September, space science, star gazers, telescope, The Red Region, The Red Stars: Observations and Catalogue Leave a comment »Journey to Red and Orange stars in September’s night sky
Color like this only grows and expands the further you travel on your Journey to the Beginning of Space and Time
Fall is in full bloom in the Northern Hemispheres of planet Earth and lovers of the reds, oranges, and bright reds on the leaves of fall will enjoy the rich, warm and colourful hues in the night sky of September and October.
If you’re heading out into the wild to enjoy Mother Nature’s bounty at this time of year? After the day walking through the forest watching the leaves on the trees turn color, from drab green to mixed shades of yellow, orange, and red. Take the time to lay back on the cold ground or your sleeping bag and check out the colors in the night sky. Even better, set up your binoculars or time machine to the stars, and enjoy the colors in the night sky by taking a “Journey to the Beginning of Space and Time.”
Star gazers have witnessed the colorful displays in the night sky for generations and our ancestors surely spent many a night staring upwards in wonder at the various colors they could see in the night sky. It was 19th-century Irish astronomer John Birmingham, who first made note of the colorful hues of light in the night sky. His ideas and the thoughts of Danish astronomer Hans Schjellerup, who had compiled a catalogue of red stars in 1866, were mentioned in Birmingham’s work “The Red Stars: Observations and Catalogue”. This catalogue contains a total of 658 red and orange stars colorful enough to delight the human senses and make your imagination dance a lively step.
Reading the introduction of Birmingham’s catalogue of red and orange stars, one notes he mentions a region of space and time he refers to as “The Red Region”. This region includes parts of the Milky Way Galaxy, between Aquila, Lyra, and Cygnus, that are filled with orange and red stars that will make the eyes dance and entice the human imagination to create possibilities beyond anything we as humans have imagined.
September is the perfect time for you to board your time machine to the stars and “Journey to the Beginning of Space and Time” to experience the Red Region. The Red Region will be well above the southern horizon, once the sun goes down. This region of space and time has eye-gems for star gazers to view in September, with reds and oranges that will make lovers of fall smile, and turn up their color sensitivity. The colorful stars in the Red Region warm sequentially through spectral classes: G (yellow), K (orange), M (red) and rare carbon class C (deep red). Astronomers have subdivided star classes from 0 to 9, with a G9 star being a little closer to orange, than yellow, and a K5 star having a color somewhere between orange and red.
All star gazers will see varying hues of red, orange, and yellow during their “Journey to the Beginning of Space and Time” that will depend on each star gazers own particular biology. In fact, we all view color slightly differently, so individual star gazers shouldn’t rely on a star’s spectral class for a visual clue to a star’s true color. Take for example, the strikingly colorful, double star Albireo (Beta Cygni) in Cygnus. Star gazers through the centuries have described its magnitude 3.1 K3 primary star as yellow, topaz, gold and orange. Its magnitude 5.1 B9 (blue-white) secondary star (34″ away) on the other hand, has been described as deep-blue, azure, sapphire and even green.
The perception of color for humans is subjective and depends on varying individual parameters that can also be a product of physiological and psychological effects, such as the strong contrasting colors of a double star, like Albireo. The colors star gazers view through their time machine to the stars can also be obscured by dust and pollutants in the air, which will redden a stars color. Stars that are low on the horizon, in comparison to higher stars, will also appear redder to viewers, just like the sun turns redder as it falls toward the horizon.
