Core Theme 2: Constellations

Transcription

1 Core Theme 2: Constellations Use astrological star sign as a hook; constellation identification; origin and history; myths and legends; observing the night sky; identify stars of different types, names and colours; investigate available astronomical resources and how to find them. Task: Observing, drawing, make up new constellation patterns and associated stories, compare with constellations in other countries to encourage global awareness.

2 Star signs and Astrology So who doesn t know their star sign?! How do you think they were set? Have a look at tonight's night sky image copied on your desk today can you see some of the signs of the Zodiac?

3 For the purpose of determining the constellations in contact with the ecliptic, the constellation boundaries as defined by the International Astronomical Union in 1930 are used. For example, the Sun enters the IAU boundary of Aries on April 19. Needless to say, the IAU defined the constellation boundaries without consideration of astrological purposes. The dates the Sun passes through the 13 astronomical constellations of the ecliptic are listed below, accurate to the year The dates will increment by one day every 70½ years, and already several have changed. The corresponding tropical and sidereal dates are given as well.

4 History Astrology consists of a number of belief systems which hold that there is a relationship between astronomical phenomena and events in the human world. In the West, astrology most often consists of a system of horoscopes that claim to explain aspects of a person's personality and predict future events in their life based on the positions of the sun, moon, and other planetary objects at the time of their birth. Many cultures have attached importance to astronomical events, and the Indians, Chinese, and Mayans developed elaborate systems for predicting terrestrial events from celestial observations.

5 We are looking at Constellations in an astronomical context! In modern astronomy a constellation is an internationally defined area of the celestial sphere. There are 88 standard constellations recognised by the International Astronomical Union (IAU) since The majority go back to the original 48 constellations defined by Ptolemy in the 2 nd centaury. The remaining were defined in the 17 th and 18 th century, the most recent found in the southern sky. There are also numerous historical constellations not recognised by the IAU, or constellations from regional traditions of astrology or astronomy such as Chinese, Hindu and Aboriginal.

6 Identification

7 We will look at 4 constellations here: Ursa Major Orion Pegasus Taurus Can you spot all four on your night sky map? To observe we must first become familiar, so we can use heavens-above.com website, Stellarium programme, a planisphere, viewer etc. When we get a clear night sky, wrap up warm, go to a dark location and allow your eyes to become dark-adjusted for at least 10min. Bring map/ iphone and torch with red filter.

8 Ursa Major Dominated by the Plough, the pointers point North to Polaris. Roughly, this is the area the Hubble Deep Field image was taken in. Ursa Major has many cultural associations.

9 Orion Orion a winter constellation, beautiful. Betelgeuse is a massive M-type red supergiant star nearing the end of its life. When it explodes (probably not in our lifetime!) it will even be visible during the day. Rigel is a B-type blue supergiant that is the sixth brightest star in the night sky.. The Orion Nebula is in the Hunter s sword. Sirius, (the Dog Star, not shown here) following at Orion s heel is the brightest star in the night sky (a binary star).

10 Pegasus Pegasus is a constellation in the northern sky, named after the winged horse Pegasus in Greek mythology. It was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy.

11 Stars of Pegasus lets look at naming etc. here: α Peg (Markab), β Peg, and γ Peg, together with α Andromedae (Alpheratz or Sirrah) form the large asterism known as the Square of Pegasus. 51 Pegasi, a star in this constellation, is the first Sun-like star known to have an extrasolar planet. IK Pegasi is the nearest supernova candidate. Spectroscopic analysis of HD b, an extrasolar planet in this constellation has provided the first evidence of atmospheric water vapor beyond the solar system, while extrasolar planets orbiting the star HR 8799 also in Pegasus are the first to be directly imaged.

12 Magnitudes

13 Taurus the Bull Has many interesting components. The brightest member of this constellation is Aldebaran, an orangehued, spectral class K5 III giant star. Its name is from al-dabarān, Arabic for 'the follower' (of the ا&%$#ان Pleiades). Bull s eye.

14 The Pleiades (M45) or Seven Sisters (Messier object 45), is an open star cluster containing middle-aged hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky. Pleiades has several meanings in different cultures and traditions. The cluster is dominated by hot blue and extremely luminous stars that have formed within the last 100 million years beautiful to look at!

15 Resources As mentioned earlier we can use some things to first become familiar with the night sky: heavens-above.com website, Stellarium programme, a planisphere, viewer etc. Lets look at using these now briefly to find the night sky for tonight and perhaps what time Orion rises? We can aslo use websites to get the children interested: BBC Sky at night Orion Plough cultural stories Moore Marathon e.g. Objects

16 To finish my favourite story Dark cloud constellations The Great Rift, a series of dark patches in the Milky Way, is more visible and striking in the southern hemisphere than in the northern. It vividly stands out when conditions are otherwise so dark that the Milky Way's central region casts shadows on the ground. Some cultures have discerned shapes in these patches and have given names to these "dark cloud constellations." Members of the Inca civilization identified various dark areas or dark nebulae in the Milky Way as animals, and associated their appearance with the seasonal rains. Australian Aboriginal astronomy also describes dark cloud constellations, the most famous being the "emu in the sky" whose head is formed by the Coalsack.

17 The "Emu in the sky," a constellation defined by dark clouds rather than the stars. An IAU interpretation would recognise Crux (the Southern Cross) above the emu's head and Scorpius on the left. The head of the emu is the Coalsack. Further information: Great Rift (astronomy)