Download A Unique Environmental Studies Program

Little Desert Nature Lodge Environmental Studies Program
A Unique Environmental
Studies Program
at the Little Desert Nature Lodge
Astronomy
Little Desert Nature Lodge
Whimpey’s Tours
© Little Desert Nature Lodge Pty Ltd 2009
Phone (03) 5391 5232
Fax (03) 5391 5217
www.littledesertlodge.com.au
1
Little Desert Nature Lodge Environmental Studies Program
Astronomy
As you move away from cities and towns and out into the bush at night, you will be surprised by
the brightness and number of stars that you can see. There are two reasons for this. One is that
there are no street lights; the other is that the air is much cleaner, being relatively free of
airborne particles.
Looking up at sky above the Lodge you will be able to see many astronomical features, even with
the naked eye, including such things as the Milky Way, the Southern Cross, the Pointers, the
Clouds of Magellan, the constellations of Orion and Scorpio, some of the planets, satellites and so
on.
With binoculars you will be able to see much more and, with a telescope, much more again. The
following information is provided to help you learn and understand a little more about our
universe.
Distances in Space
Because our universe is so big, and the distances so great, we use a measurement known as a
"light year". That is, the distance light will travel in one year, at the speed of 300,000 kilometres
per second (about 9,5000,000,000,000km per hour). We sometimes use similar forms of
measurement when we say that it is about 5 hours by car from Melbourne to the Little Desert
Lodge, or that it is about a five minute walk from your home to the shops.
The Milky Way
This is the galaxy in which we live. It is a spiral galaxy, about 80,000 light years across and our
solar system is located in one of the 'arms' of the spiral.
Astronomers believe that the universe was formed about 15,000,000,000 years ago, while our
planet Earth was formed only about 4,500,000,000 years ago.
When we look at the Milky Way, we are actually looking in towards the centre of the galaxy. If
we look at the Milky Way through binoculars or through a telescope we will find that it is made
up of millions of stars.
Galaxies are made up of millions of stars grouped together. We could perhaps think of galaxies as
being like cities, but which have stars instead of buildings. Galaxies come in a variety of shapes
and sizes, but the most common types are globular (shaped like a globe), disc-shaped (a bit like a
dinner plate). The "Clouds of Magellan" are satellite galaxies of our Milky Way Galaxy and our
nearest galaxy is 'Andromeda', which is not easily seen from the southern hemisphere, but can
occasionally be seen low on the northern horizon in late summer with the aid of a telescope. It is
over 2,200,000 light years from earth, and is at least 130,000 light years from one side to the
other.
The Southern Cross. This is perhaps our best-known group of stars, which are featured on
our national flag. There are five stars in the Southern Cross, and each has a name, according to
its magnitude or "brightness". Most stars or astronomical features are given Greek names, often
beginning with letters of the Greek alphabet. Thus to astronomers, the Southern Cross is
known as "Crux", and the stars which make up the Southern Cross are Alpha Crucis, Beta
Crucis, Delta Crucis, Gamma Crucis and Epsilon Crucis.
© Little Desert Nature Lodge Pty Ltd 2009
2
Little Desert Nature Lodge Environmental Studies Program
The Pointers. Not very far from the Southern Cross you will see two quite bright stars.
These are known as "The Pointers". They form part of the constellation of "The Centaur" and,
being the two brightest stars in that constellation, are called Alpha Centauri and Beta Centauri. If
you look at Alpha Centauri through a telescope you will find that is actually is two stars (a binary
star), and they revolve around each other once every 80,000 years.
Alpha Centauri is particularly interesting to astronomers because it is the nearest star visible to
the naked eye, being 'only' 4.3 light years from earth.
Another star in the same constellation, Proxima Centauri, is actually our closest star, at 4.2 light
years from earth, but it is only visible through a telescope.
The Coal Sack. Close to the Southern Cross you may see a very dark patch called the "Coal
Sack". This is a cloud of very dark dust or gas and even though there may be stars behind it,
their light cannot shine through.
The Clouds of Magellan. These clouds were first described by the explorer Magellan, and
they are actually two satellites of our own Milky Way galaxy. These clouds are easily seen on a
clear night, and they lie about 150,000 light years from earth.
Close to the Small Mageflanic Cloud you may see what looks like a fuzzy star. This is the great
global cluster 47 Toucannae, about 20,000 light years away.
Pleiades, or the 'Seven Sisters'. In the northern sky you should be able to pick out the cluster of
stars called Pleiades or the Seven Sisters. This is a cluster of young stars and through a telescope
you may see the remains of the nebula from which the stars were created.
The Constellation of Orion. ln the northern sky you should be able to pick out the
constellation of Orion the Hunter. In the southern hemisphere Orion is upside down, and like
many of the constellations, you need a bit of imagination to see the figure of Orion the Hunter
formed by the stars.
We can usually make out a shape of what we call "The Saucepan". Actually one side of the
saucepan forms Orion's belt, and the handle of the saucepan is Orion's sword hanging from his
belt. However, if you look at the second star in the handle of the saucepan (Orion's sword)
through a good pair of binoculars or a telescope you will find that it is not a star at all, but is a
brightly-glowing cloud of gas, known as the 'Great Nebula of Orion'.
Orion's head is the bright red star Betelguese, which is easy to find. Other bright stars that you
might be able to locate are Archenar, Sirius and Rigel. Once you are able to locate and identify a
few stars, you will soon be able to find many more stars and constellations.
© Little Desert Nature Lodge Pty Ltd 2009
3
Little Desert Nature Lodge Environmental Studies Program
Worksheet - Finding the South Celestial Pole.
In the northern hemisphere there is a star (the pole star), which is almost directly above the
north pole, and people can navigate at night by this star.
In the southern hemisphere we don't have any such stars above the south pole, but we can use
some of our well-known star groups, the Southern Cross and the Pointers, to find the spot in
the sky above the south pole, called the South Celestial Pole (SCP).
This can be done by several methods, but the two most common are as follows:
1. Using the Southern Cross: Imagine the Southern Cross to be an old-fashioned kite, with a
long tail. If you go three and a half times the width of the kite down an imaginary tail, you will
find the SCP.
The Southern Gross
SCP
2. Using the Southern Cross and the Pointers: If you draw an imaginary fine through the long
axis of the Southern Cross, and another imaginary line bisecting the Pointers, the spot where the
two lines meet is the SCP
The Pointers
The Southern Cross
SCP
© Little Desert Nature Lodge Pty Ltd 2009
4
Little Desert Nature Lodge Environmental Studies Program
Worksheet - The Planets
Because planets "wander" or move against the background of "fixed" stars, different planets will be
visible at different times of the year. The planets which you may be able to see include Jupiter,
Saturn, Venus and Mars. By looking in the daily newspapers in the weather report section, you
will be able to find out at what time of day or night each of these planets will rise and set.
Questions:1.
Give two reasons why we can see more stars when we are away from cities and towns:(1) ………………………………………………………………………………………………
(2) ………………………………………………………………………………………………
2.
In which galaxy do we live?……………………………...……………………………………….
How long ago do astronomers believe that it was formed?……..……………………………...
What is the distance across the galaxy?………………………..………………………………..
3.
What is the name of our nearest galaxy?……………………..…………………………………
How far away from the earth is it?……………………………...………………………………
4.
What is the name of our closest start?………………………………………………………….
How far from earth is it?……………………………….………………………………………..
5.
What are the "Clouds of Magellan"?……………………..…………..………………………….
How far from earth are they?……………………………..……...……………………………..
6.
What is unusual about the brightest start of "The Pointers"?……….…………………………
………………………………………………………………………………………………….
7.
What is interesting about the second star in the handle of the "Saucepan" or Orion's sword
………………………………………………………………………………………………….
8.
Which of the planets might you be able to see in the night sky?
………………………………………………………………………………………………….
9.
How would you find out what planets would be visible on any given night?
………………………………………………………………………………………………….
© Little Desert Nature Lodge Pty Ltd 2009
5