Pagina's

Showing posts with label stars. Show all posts
Showing posts with label stars. Show all posts

8/8/11

Brightness and magnitude of stars

If you look up to the sky you see stars with different brightness. Some stars are very bright, while others are just faint. This is partially because some stars are more luminous than others, but also because some stars are much further away than others. For an example have a look at the two pointers of the Southern Cross for instance. Alpha Centauri (the one the furthest from the Cross) seems brighter than Beta Centauri, also called Hadar (the one closest to the Cross). The reason for this is its proximity; it is in fact our closest stellar neighbour. The double stars in Beta Centauri are much more luminous than the triple stars in Alpha Centauri, but they are about 120 times further away. This causes the star to look less bright because the light is spread out over a much larger area as it travels away from the star.
Absolute Magnitude
To compare how stars would look if they were all at the same

8/4/11

Astronomy for everyone

You don’t need an expensive telescope to enjoy astronomy. There is a lot to see and view with the naked aye or with a good pair of binoculars. This is how Corné and I also started, just looking up at the sky and curious to learn more about it.
Before you go out to look at the stars, take a little time to prepare. You will need to find a dark place, as far away from artificial lights as possible or at least shielded from direct light. Before you set out, have a good look at the star chart or planisphere so you have an idea of what you can see. For special phenomena, like eclipses and meteor showers etc. there are sky guides available or you can look at the internet. Your eyes will need about 20 minutes to fully adapt to the darkness and, as the pupil opens, more detail and fainter objects will become

7/28/11

The Milky Way

On a clear, moonless night away from the city lights, you can see a pale white band stretching across the sky. This hazy band of light is our own inside view of the city of stars that form the galaxy we are part of, the Milky Way Galaxy.
There are many myths involving the formation of the Milky Way, but the best known is probably the Greek myth of Hercules. In Greek mythology, Hercules was the son of Zeus and a mortal woman. It was said that when Zeus’ wife, while suckling Hercules, found out that his mother was a mortal woman, she pulled her breast away and her milk flowed among the stars.
But what is the Milky Way really?It is a spiral shaped galaxy, a vast collection of stars, gas and dust of which the solar system with our Sun and its system of planets, is a part. We are located about halfway

7/26/11

Scorpius

Scorpius is one of the easier recognisable constellations, not to confuse with Scorpio, the name for the astrological sign of the Zodiac. At the moment Scorpius is right above us here in the southern hemisphere.
In the Greek mythology the scorpion was send by the gods to kill Orion, the great hunter, after he had boasted to kill all animals on Earth. They fought for a whole day and finally were exhausted. When Orion fell asleep the scorpion stung him, Orion woke up and killed the scorpion but then died from the poison. The gods placed them amongst the stars in the sky but far apart so they could not fight anymore.
The tail of Scorpius lies in the Milky Way, the city of stars in which we live. When we look at the tail of Scorpius

7/19/11

Our closest star, the Sun

The Sun is our very own star. It gives us light, energy and warmth and without it, life could not exist on Earth. But what is a star and what kind of star is our Sun?

A star is a huge sphere of very hot, ionised gas. Because of the pressure and temperature in the core of a star, a nuclear reaction takes place that forms helium from hydrogen. This generates enormous amounts of energy, which is slowly carried outward until it finally reaches the surface and radiates out into space in the form of heat, light and other forms of radiation. This journey of energy to the surface can take up to a million years. Our Sun is a quite small and average star in the main sequence. Its surface has temperatures of about 5.500 degrees Celsius, which results in a yellowish light. Hotter stars will appear

7/12/11

The edge of the universe

Distance does strange things to our perspective. Astronomers have found a galaxy at the astonishing distance of 13 billion light years. It was born soon after the Big Bang and since its light has travelled so long to reach us, we see it as it was just after it was born. So the image we see is of a very young galaxy, at the same time it is very old, 13 billion years to be precise. Viewing galaxies so far away in our ever-expanding universe, introduces several bizarre twists in understanding. The very old, yet young galaxy is one of the least bizarre. Another thing that happens when you look at something that far away is that it looks bigger than it should at that distance. At the same time it looks dimmer than one would expect. The reason for this is

7/6/11

Breathtaking stars

As a child I already had a fascination for stars. I think I was about nine years old when my brother in law pointed out the Big Dipper to me for the first time, and from that moment I was hooked. Although I already owned a book about astronomy when I still lived in the Netherlands and had looked up to the breathtaking sky of the southern hemisphere during our travels, the real fascination came when I came to live here in South Africa. Especially in winter the sky here is so clear that you can see the Milky Way beautifully.
Corné also got interested and

7/3/11

Saturn, Lord of the rings

The planet Saturn can be seen beautifully now in the night sky. Saturn is one of the most fascinating planets because of its rings. Through our 10 inch telescope you can clearly see the rings sticking out on both sides of the planet. Some of the larger moons can be seen as well. Saturn is one of the gas planets and the second largest planet in our solar system, after Jupiter. The planet is about Milky Way. You can see Scorpio beautifully and Sagittarius is rising. The Southern Cross is getting lower now and Arcturus in the constellation Bootes is one of the brightest stars in the sky. It is a great time of year if you love astronomy like us.

6/30/11

introducing myself

Hi,
I'm Miriam and since 2004 I live with my husband Corné in South Africa, in the Balule Private Nature Reserve to be precise. We have build our own lodge here in the bush where we receive guests. Our two sons, Niels of four and Dennis of two are born here and grow up in this beautifull environment.


The reserve where we live is close to the famous Kruger Park and all animals that live there, including the Big Five, occur in our park as well.
Life here in the bush