Constellations Flashcards
Describe the appearance of stars.
Stars appear as points of light in the sky. They are like our Sun and can vary in size and heat.
Describe the appearance of double stars.
Many stars are binary stars and consist of two or more stars that share a gravitational bond. These are called double stars although this name also applies to stars that look binary because of the angle we see them but are not connected.
Describe the appearance of asterisms.
An asterism is a pattern of stars that may or may not be linked to a constellation.
Describe the appearance of constellations.
A constellation is a group of stars that appear to make a pattern in the sky.
Describe the appearance of open clusters.
Open clusters are groups of stars close to each other in space. They form no specific symmetry and are usually very bright, indicating that they are young stars.
Describe the appearance of nebulae.
Nebulae (the plural of Nebula) are blurry patches of light in space that are not other galaxies but are in fact mostly in our own galaxy.
Describe the appearance of globular clusters.
Globular clusters are spherical shaped with more stars nearer the nucleus. They resemble a fuzzy ball.
How are stars in a constellation labelled?
Stars are labelled according to their brightness. The system that astronomers use is the Bayer Designation, named after the German astronomer Johann Bayer who catalogued stars by using the Greek alphabet to represent their brightness where Alpha is the brightest, Beta the next brightest etc.
Demonstrate an awareness of how the official list of constellations became established and cultural differences in this list.
The list of constellations we use today was handed down by a script written by Greek astronomer Ptolemy who was born in the first century. Many of the constellations were based on mythology, mostly Greek mythology.
Constellations were added to the common list when explorers charted the southern hemisphere constellations. The list was formalised into 88 constellations by the International Astronomy Union in the 1920s.
The list does not take into account cultural references to the constellations. The Chinese, Indian and Aboriginal cultures had their own constellations.
Demonstrate the use of pointers‘ and other techniques to find Arcturus and Polaris from the Plough.
The two stars on the pan end of Ursa Major point (from bottom, Merak, to top Dubhe) to Polaris in Ursa Minor.
The Plough is also useful to find Arcturus, a red star in Bootes. Follow the path of the ‘handle’ of the Plough to find Arcturus.
Demonstrate the use of pointers‘ and other techniques to find Sirius, Aldebaran and the Pleiades from Orion.
The stars in the belt of Orion can point westwards and down to a very bright star called Sirius, the Dog Star, in the constellation of Canis Major (The Great Dog).
If you follow the path of the 3 stars in the opposite direction you will come to the bright red star Aldebaran in Taurus and the Pleiades Cluster.
Demonstrate the use of pointers‘ and other techniques to find Fomalhaut and the Andromeda Galaxy from the Great Square of Pegasus.
If you use the bottom right and top left stars of the square you can use a line to find the Andromeda Galaxy which is barely visible on a clear night in an area of low light pollution.
Using the top right and bottom right stars of the square you can follow the line down to Fomalhaut. Bear in mind that Fomalhaut is only visible from southern parts of the UK for a few months of the year and will be very near the horizon.
Why are some constellations are visible from a given latitude throughout the year, but others are seasonal.
If you lived at the Poles you would see the same stars throughout the year. However in the UK (between latitudes 50 and 60 degrees north) we see circumpolar constellations, such as Ursa Major througout the year and some constellations, such as Orion, for a few months of the year.
This is due to the seaons on Earth. The Earth’s axis is titled at an angle of 23.5 degrees to the ecliptic. This results in us seeing some constellations throughout the year and some only part of the year.
