under the African sky

beautiful nebula

2013-09-01T23:37:00.002-07:00

Located 8,000 light-years from Earth, the Eta Carinae star system is captured in this stunning infrared image from NASA'S Spitzer Space Telescope.

From a cosmic crash to a mini-eclipse—see our favorite photos from space:http://on.natgeo.com/14NNNly

Solarflares from our active Sun

2013-08-02T06:04:00.001-07:00

This year our Sun is very active. It is in it's most active part of it's cyclus and that means regular solarflares that are a lot stronger then ususal.
Once every eleven years the magnetic poles of the Sun change place, causing a low magnetic field. This allows more and stronger explosions on the surface of the Sun, called solarflares. If a solarflare is strong enough it can cause probems on Earth with electricity and radio since the flares send electro magnetic radiation into space.

Solarflares are classified into three categories. The C category is the weakest and will cause no problems on Earth where the M category can cause radio problems around the poles. The X category is the strongest and if the outburst is pointed in the direction of the Earth it can cause problems.
The Sun always has small solarflares that never reache the surface of the Earth but can cause the beautiful aurora above the poles. This year however it will reach it peak in activity and already in May it produced three solarflares of the X category. Also in July a strong solarflare was registered by the NASA.
So far the solarflares have caused no problems and come nowhere near the strength of the worst solarflare ever recorded in September 1859. That one was visible with the naked eye and caused chaos, in these times where we have become so dependend on electricity and devices the effect would be even greater.
Let's hope this cyclus will pass again with a minimum of disruption.

A short history of astronomy

2011-08-20T01:03:00.000-07:00

Astronomy is the oldest science by far. As long as mankind exists we have looked up to the skies and wondered what was out there. Almost every culture throughout history has studied the Sun, Moon and stars, and watched how celestial bodies move across the sky. For early civilisations, like the ancient Egyptians, astronomy was a way to keep track of the changing seasons. They used it to know when it was time to plant and harvest crops and it was used to make calendars and sundials to keep track of time. In 1000 BC, Indian and Babylonian astronomers had already calculated length of a year as 360 days (which resulted in a 360 degree circle, with each degree representing a solar day). Later the ancient Egyptians refined this calculation to 365.25 days. The most important discoveries
of ancient astronomers included how to find the north, south, east and west. This knowledge enabled the precise orientation of buildings like temples and burial monuments and helped to produce accurate terrestrial maps. Later on it was used for navigation at sea as well. The ancient Greek lay the base for scientific astronomy. After the decline of the Greek city-states, the most important advances in astronomy were achieved by Arabic scholars. This period lasted from about 620 AD until the 15^th century, when European astronomers took over again.
For centuries astronomers had placed the Earth at the centre of the Universe. In the 16^th century the Polish Nicolaus Copernicus published a ground-breaking treatise about a Sun-centred, or heliocentric, Universe. This explained many, previously puzzling, observations because there were now two types of planets; those inside the Earth’s orbit and those beyond. In 1608 a Flemish spectacle-maker invented the telescope and the news spread quickly. The Italian Galileo Galilei made his own telescope and became the founder of the telescopic astronomy. He provided the proof that Copernicus was right. In 1687 Isaac Newton published the first clear mathematical definition of gravity, it revolutionised astronomy and physics. In the 18^th and 19^th century there was great progress in science due to improved scientific methods. During the 19^th century a new field emerged in astronomy; astrophysics. Before, astronomy had been mainly about observing the movement of planets and stars, whereas astrophysics applied mathematics, physics and chemistry to examine radius, mass, temperature and composition of celestial objects.
In the beginning of the twentieth century astronomers realised that there were billions of galaxies, millions of light years apart, instead of just our own Milky Way galaxy. They also started to understand the sources of stellar energy. More and bigger telescopes were build and became available for a larger number of astronomers. In the 1950’s the era of spaceflight started and travel beyond Earth became a reality. The dawning of radio, infrared, ultraviolet, x-ray and gamma ray astronomy, together with space probes and telescopes in space offered a whole new perspective to the Universe. Although we have learned a lot since first men looked up to the sky, there is still much

more to be learned and the more we learn, the more we realise how much we still don’t understand.

Regards from the bush,
Miriam

What are constellations?

2011-08-11T01:35:00.000-07:00

The first constellations were patterns of stars that ancient peoples used for navigation, timekeeping and storytelling. Most constellations used now, stem from patterns recognised by ancient Greeks and Romans, and they carry myths and legends from that time. However the ancient Greeks were not the first to recognise patterns. The 47 constellations they used were introduced by a Greek astronomer called Euxodus, who had learned them from priests in Egypt. They in turn had adopted them from Babylonian culture and they were originally created by the Sumerians around 2,000 BC. The oldest surviving star catalogue dates from

the 2^nd century AD and was written by the Greek astronomer Ptolemy. It records the position and brightness of one thousand stars, arranged in 48 constellations. In the 10^th century AD, an Arab astronomer updated this book and included many Arabic names for stars that are still used. No more constellations were added until the end of the 16^th century, when Dutch explorers sailed to the East Indies. From there they could observe the southern sky that was below the horizon in Europe. Two Dutch navigators, Pieter Dirkszoon Keyser and Frederick de Houtman, catalogued nearly 200 new stars and formed twelve new constellations. Other astronomers filled in the gaps between those constellations and nowadays the sky is divided into 88 areas, or constellations. The names and boundaries were officially agreed on by a resolution of the International Astronomical Union in 1930. The constellation names are in Latin, although several are derived from the Greek.

Sixty-eight of those constellations are visible from South Africa, the other twenty lay above +30 degrees and are therefore always below the horizon. Along those twenty constellations are Ursa Major and Ursa Minor, the best known constellations of the northern hemisphere. Although at some point in winter we can see a few stars of Ursa Major, very low on the horizon.
Most people know, at least by name, the twelve constellations of the Zodiac that are used in astrology. The Zodiac is the band of stars along the ecliptic through which the Sun, Moon and planets move. Here in the southern hemisphere the Southern Cross is the most famous constellation.

Until next time, clear skies,
Miriam

Brightness and magnitude of stars

2011-08-08T23:26:00.000-07:00

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
distance, astronomers use a measure of intrinsic brightness called the absolute magnitude scale. This scale uses high positive numbers for the dimmest stars and negative numbers for the brightest ones. A star’s intrinsic brightness is related to its luminosity, which is the amount of energy it radiates into space per second. Once a star’s distance is known, its absolute magnitude can be determined and from this its luminosity. Stellar luminosities are generally expressed as factors of the Sun’s luminosity. There is a very large range of stellar luminosities, from less than one ten-thousandth to a million times that of the Sun.

Apparent magnitude
A stars brightness as seen from the Earth on the other hand, is described by its apparent magnitude. Again the smaller the number of a star’s apparent magnitude, the brighter the star. The faintest stars detectable with the naked eye have an apparent magnitude of +6, whereas the apparent magnitude of most bright stars lay between +2 and 0. The four brightest stars have negative apparent magnitudes. The brightest star in the sky is Sirius. It is, with 8.6 light years, the ninth closest star to Earth and has an apparent magnitude of -1.46. Sirius is a binary pair consisting of Sirius A (a main-sequence star that has twice the mass of the Sun and that is 23 times more luminous) and its companion, a white dwarf.

I hope you found this interesting again.

Happy stargazing
Miriam

Three galaxies

2011-08-06T00:02:00.000-07:00

A beautyfull picture of three galaxies close toghether in Leo. http://apod.nasa.gov/apod/ap110803.html

Astronomy for everyone

2011-08-04T04:10:00.001-07:00

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

visible. If you need to use a torch, use a red filter, this will help you to keep your eyes adapted to the darkness. Although the Moon is beautiful to look at on its own, for stargazing it is best to avoid nights with bright Moon. The best way to get to know the night sky is to start with a few bright stars in a familiar constellation. From there you can work your way out to other constellations, using the star chart as a guideline. With the naked eye you can get to know the constellations, trace the paths of the Moon and the planets, and observe the brightest of the deep sky objects. Once you know your way around the constellations a bit, you can start using binoculars to expand your view.

The most important quality when choosing binoculars are the two main numbers describing the optical qualities; for example 7 x 50. The first number is the magnification, for a newcomer a magnification of 7 or 10 times is adequate. A bigger magnification only makes it harder to find objects. The second number is the aperture, or diameter of the objective lens, measured in millimetres. This tells you how much light the binoculars will gather, which is important for seeing faint objects. For night-sky viewing, an aperture of at least 50 millimetres is preferable.
When looking through binoculars you can steady them by letting your elbows rest on something. With binoculars you can look at the Milky Way, the Pleiades, the Orion nebula or the Andromeda Galaxy (M31) for instance. You can also observe the Moon, Jupiter and its moons and the phases of Venus. It is an excellent way to practice finding objects in the sky and it will be very helpful if you want to start using a telescope.

Whether you are an enthusiast starting amateur or just interested in the beauty of the stars, try visiting a nearby observatory or planetarium, it will be worth your wile.

Happy stargazing
Miriam

Meteor showers

2011-08-02T01:50:00.001-07:00

This time of year there are several meteor showers that we can see. From half July till half or the end of August we can see the Pisces Australids (between 21:30 and 5:00 hour), the S. Delta Aquarids (between 22:00 and 5:00 hour) and the Alpha Capricornids (between 20:00 and 4:00 hour). But what are meteor showers?

A meteor, or “shooting star”, is a particle of rock or dust that enters the Earth’s atmosphere and causes a streak of light when it burns up. In general meteors appear in the upper atmosphere, at an altitude of between 80 to 120 kilometres and disappear between 60 and 80 kilometres high. If the object is big enough, some of it will reach the surface and is then called a meteorite. Most meteors entering the atmosphere are sporadic, particles travelling through space in isolation. But several times a year, the Earth passes through streams of particles left behind by comets

in their passage around the Sun. At these times you can see more meteors than usual and they all seem to originate from the same area in the sky. This is called a meteor shower. Meteor showers are named after the constellation they seem to originate from, so the Pisces Australids originate from the constellation Pisces Australis, the S. Delta Aquarids from Aquarius and the Alpha Capricornids from Capricorn.

All three of these meteor showers reached their height in the end of July but will still be visible until mid or end August. Not all meteor showers will show you the same amount of “shooting stars” and the best viewing is when the constellation is high in the sky. All three of the mentioned meteor showers have favourable conditions and we have already seen a fair amount of meteors while stargazing with guests or even sitting around the campfire.

Regards from the bush
Miriam

great picture

2011-07-30T03:53:00.001-07:00

Another great picture from NASA

The Milky Way

2011-07-28T00:19:00.000-07:00

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

from the centre, on the edge of a spiral arm called the Orion-arm. The band of light we see is the light of millions of stars that lie in the disc of the galaxy and often are too far away to be seen as separate stars with the naked eye. Most of the visible mass consists of stellar material like gas, stars, dust and planets, but about 90 percent of its total mass is made up of invisible “dark matter”, which remains a mystery still to be explained.

The geography of the Milky WayAt the very centre of the Milky Way lays a massive black hole. This core, or nucleus, of the galaxy is surrounded by a bulge of stars that grow denser closer to the centre. This forms an ellipsoid of about 15,000 by 6,000 light years, the longest dimension lying along the plane of the Milky Way. Around this, young stars form a spiral pattern. The Milky Way is about 100,000 light years in diameter and about 2,000 light years thick. The spiral arms are named after the constellation that they are most prominent in. The brightest arm is that in Sagittarius, while we are located in the Orion arm.

The closer an object is to the centre, the faster it will move. The Sun travels around the galactic centre at about 800,000 kilometres (500,000 miles) per hour, taking about 225 million years to complete one orbit. Our Milky Way is quite a large galaxy and part of what is called “the local group” of galaxies. This local group also contains the Magelhanic Clouds and the Andromeda galaxy, which are, despite the enormous distances, our closest neighbours.

From Balule I wish you clear skies and happy stargazing.
Miriam

Scorpius

2011-07-26T01:42:00.000-07:00

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
and the next constellation, Sagittarius, we look towards the centre of our galaxy. The central bulge is obscured by opaque foreground clouds however and can’t be seen. Still most of the light we see in this area comes from about 25,000 light years away.

In the body of Scorpius we see the brightest star of the constellation, Antares. Its name is Greek for “rivalling Mars” (anti-Ares, where Ares was the Greek name for the God of war, which was called Mars by the Romans) since it is very bright and reddish in colour, just like the planet. However Mars is a tiny planet while Antares is a red super-giant, probably about 200,000 times greater in diameter. The reason they look similar is because of the huge difference in distance. Where Mars is only 5 to 20 light minutes away, Antares lies at a distance of about 600 light years. It is the 15^th brightest star in the sky and about 10,000 times more luminous than our Sun. Estimates of its diameter vary from 280 to 700 times that of the Sun, but it is only about 15 times more massive than the Sun and has therefore a very low density. The reddish colour is the result of a relatively low surface temperature and its brightness fluctuates from 0.9 to 1.2 every four to five years.

In Scorpius you can also find some nice open and globular clusters that can be viewed with binoculars or small telescopes. The nicest ones to observe are M6 and M7, close to the tail of Scorpius. These are two prominent open star clusters that can be seen with the naked eye as hazy patches. With binoculars you can see tens of individual stars in each. M7 is about 8,000 light years away and M6 twice as far. M6 is also called the butterfly cluster because of its shape when viewed with binoculars. There are some other clusters in this constellation, like M4 close to Antares, but they are fainter and less nice to view with amateur telescopes.
Close to Scorpius pinchers lays Scorpius X-1, this is the strongest X-ray source in the sky. It consist of a 13^th magnitude blue star, orbited by a neutron star.

All in all Scorpius is an interesting constellation to view.

Happy stargazing from Balule,
Miriam

Distant galaxy

2011-07-24T05:05:00.000-07:00

NASA regularly posts great pictures of the universe, with a short explanation. Like this picture of a distant galaxy called NGC 2403.

Regards from the bush
Miriam

Rings around the planets

2011-07-21T02:43:00.000-07:00

Saturn is well known for its rings, but fewer people know that the other gas giants have rings as well. They are less spectacular and not visible with amateur telescopes. They were only discovered in the last decades of the twentieth century. Many of the mechanisms behind some of the ring’s properties still remain under debate. Planetary rings have always been incidental discoveries. They have fascinated and mystified for as long as we have known about them.

Jupiter
In 1979 the space probe Voyager 1 discovered the rings around Jupiter. Technically they are visible from Earth with the strongest telescopes, but they are faint and were therefore overlooked so far. The main ring is flat and about 7.000 kilometres (4.350 miles) wide and less then 30 kilometres (18 miles) thick. It is the brightest component of the ring system. Outside it lay

the two flat gossamer rings, which are much fainter and entirely made of dust. Inside the main ring lies the 20.000 kilometres (12.400 miles) thick, doughnut shaped halo.

Saturn
The ring system around Saturn is not only the most spectacular in our solar system, but also the most complex. Galileo first saw it in 1610 but did not know what it was and referred to it as “handles”. Only in 1655 the Dutch astronomer Christiaan Huygens identified it as rings with his stronger telescope. The rings are made of dust and ice particles, ranging in size from small grains to big chunks of several metres (yards) across. They even have a very thin atmosphere of oxygen. Their complicated structure is likely due to the gravitational effects of Saturn’s moons. The objects in the rings are very reflective and can therefore easily be seen, except when the rings appear edge-on.

Uranus
In 1977 astronomers discovered the rings around Uranus. This ring system is second in complexity after that of Saturn and consists of eleven separate rings. They are probably made of water ice and some organic material, which makes them very dark. Scientists believe that the rings may only be 600 million years old, very young compared to the rings of Jupiter who are believed to have formed together with the planet.

Neptune
When the Voyager 2 studied Neptune in 1989, the last known ring system of our solar system was discovered. These rings are extremely faint and dusty. There are five rings of dark, likely organic, material and a dim, unnamed ring may lay even further out. The outermost of the known rings is divided into five distinct “arcs” and is the only known planetary ring to do so.

regards from the bush
Miriam

Our closest star, the Sun

2011-07-19T02:32:00.000-07:00

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

bluish, while cooler stars will seem orange or reddish. With an age of about 4.6 billion years, our Sun is halfway through its lifecycle. The gravity of the Sun had captured all sorts of other material in orbits around it. Besides our Earth and Moon, there are seven other planets with their moons, several dwarf planets, asteroids, meteoroids and comets. They all orbit the Sun in some way and are therefore part of the solar system.

Since the Sun is the closest star and we are so dependant on it, it has been intensely studied. Since 1960, series of space probes and satellites have been launched by NASA and other organisations to collect data about the Sun. Here a few important missions.

Between 1960 and 1968 the Pioneer space probes 5 to 9 (USA) orbited the Sun and studied solar wind, solar flares and the magnetic field. In 1974 and 1975 the Helios 1 and 2 (USA and Germany) passed close to the Sun’s surface. They measured the solar wind and the Sun’s magnetic field. In 1980 the Ulysses (USA and Europe) was the first to orbit the Sun’s poles. In 1991 the Yohkoh (Japan, USA and UK) was launched. This was an Earth orbiting satellite that collected data for ten years. In 1995 the USA and Europe launched SOHO (Solar and Heliospheric Obeservatory) studying the Sun’s interior as well as events on its surface at an orbit of 1.5 million kilometres (930.000 miles) from Earth in the direction of the Sun. Although we know a lot about the Sun already, there is still much more to learn.

Regards from the bush
Miriam

A Moon Corona

2011-07-14T09:11:00.000-07:00

Yesterday evening, we sat a round the campfire with our guests. It was almost full Moon but it was quite clouded. A little later in the evening the sky became clearer, except for some fast moving, high clouds. Then we saw something beautiful; as the thin clouds passed the Moon, a darker ring formed around it at a little distance. At some point the ring had even some colours in it and almost looked like a pale, circular rainbow. When the clouds moved on, the corona disappeared again.
Corona’s are produced by refraction of the moonlight (which is of course reflected sunlight) from ice crystals in the upper atmosphere. The hexagonal (6 sided) shape of the ice crystals focuses the light into a ring. If there are few ice crystals, you will see no clouds but a thin ring
will form at a little distance from the Moon. This is called a halo. In this case the thin clouds provided more ice crystals, which resulted in a thicker band around he Moon, called a corona. The colours sometimes seen are the result of the prism-effect of the hexagonal ice crystals. This separates the light into its various colours because each colour bends slightly different.

Anatomy of the Moon halo

The ring that sometimes appears around the Moon is caused by the moonlight being refracted, or bend, by ice crystals high in the atmosphere. These hexagonal (6 sided) crystals, bend the light at a 22 degree angle, creating a halo 22 degrees in radius, or 44 degrees in diameter.

Weather folklore

Folklore has it that a ring around the Moon is a sign that bad weather is coming, especially in winter. In many cases this may be true. So how can a ring around the Moon predict the weather?
The ice crystals that produce the halo are a sign that there are high altitude, thin cirrus clouds present that normally precede a warm front by one or two days. Typically, a warm front will be associated with a low pressure system, which is commonly referred to as a storm. The days before this storm arrives are usually nice and warm.
In ancient times they believed that the number of stars inside the ring will tell you how many days you have before the storm arrives but if there is any truth in that….?

Lunar halo’s and even corona’s are in fact fairly common, especially around full Moon. So don’t forget to look up to the night sky every now and again. Even when it is clouded there can be something interesting to see!
Regards from the bush
Miriam

The edge of the universe

2011-07-12T06:44:00.000-07:00

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
that space has stretched the image all the way that it travelled, dramatically weakening the light and thus making the image dimmer than you would expect. But why does it appear bigger than you would expect? This is because our universe expands and the speed at which it does this increases with distance. So when the light left this faraway galaxy, it was only about 3.35 billion light years away. Therefore it is logical that the image appears bigger than you would expect, the size of the image does not change over time. This also means that, although it took the light 13 billion light years to reach us, the galaxy is now actually 30 billion light years away and moves further away from us with increasing speed.

Now consider cosmic boundaries. The first stars or proto-galaxies might have formed as early as 100 million years after the Big Bang. Their size would be of an object just 1.2 million light years away, while their brightness would indicate the inconceivable distance of 1.2 trillion light years! Their actual distance would be about 38 billion light years. This roughly marks the edge of the visible universe, but objects do not end here. Most galaxies were so far away when they formed, that their light would never reach us anyway. This would mean that a large part of the universe lies “over the horizon” and where does that end? No one is sure, but it is likely that the universe was, is and always will be infinite.

This is difficult to grasp and it’s amazing that scientists have discovered so much about things that are so far away and a universe that is so big that we can’t even imagine it. This is one of the reasons astronomy fascinates me so much.

Regards from the bush
Miriam

Our closest neighbour, the Moon

2011-07-08T03:00:00.000-07:00

The Moon is our only natural satellite. Despite its proximity to Earth and the fact that man has visited the Moon, there are still many questions about the Moon. Scientists still struggle to answer some fundamental questions like: What is the nature of the Moon’s core? What is the structure of the mantle? And, despite recent evidence of substantial water on the Moon, why is there so much less than on Earth? According to the most accepted theory, the Moon formed roughly 4.5 billion years ago, when a large body the size of Mars hit the young Earth. The debris of both the impacting body and the Earth’s outer layers formed our Moon. Almost immediately, gravitational forces
locked it into synchronous rotation, with one side always facing the Earth.

The Moon probably has an iron and nickel core, which is quite a bit smaller in proportion to its radius than that of the Earth. The core is probably surrounded by a mantle and finally a crust. The crust on the far side of the Moon is about twenty kilometres (13 miles) thicker than on the side facing Earth, this is one third of the thickness. Scientists still have no idea what could have caused this. In its early years there was volcanism on the Moon. Dark volcanic plains cover much of the Moons near side, while the far side is practically devoid of them. Although the surface lava has long since cooled, the interior remains hot. It is believed that the inside of the Moon still has temperatures of 1.300 degrees Celsius (2.400 degrees Fahrenheit) and it will probably take several hundred million years before the interior finally cools off. The Moon seems hotter on the side that faces the Earth; scientists now argue if this is because the crust on this side is thinner, or that the crust is thinner because of the heat. It is a bit like the question of the chicken and the egg.

The Moon also has seismic activity. These moonquakes are shallow ones and less violent than some recorded on Earth. The largest ever recorded registered 5.9 on the Richter scale, modest by Earth standards but still a good-sized shake. These moonquakes are partially caused by tidal stresses (induced by the changes in the Moon’s distance to Earth) and the shrinking of the Moon while it slowly cools down.

Enough questions still about our closest neighbour even though all its craters are mapped and even the far side has been explored. Even if lunar science would get priority, the Moon will continue to guard its secrets. But not forever, once we will have colony on the Moon and eventually it will have to surrender its secrets. Until then we can always look up to its familiar face and see it go through its monthly phases.

Regards from the bush
Miriam

Breathtaking stars

2011-07-06T03:13:00.000-07:00

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
together we watched the beautiful stars that we knew so little about at that stage. We learned some basic knowledge about the Southern Cross and Scorpion from friends who were guides. I knew Orion from when I lived in the Netherlands although the constellation is upside down here on the southern hemisphere. Slowly our knowledge grew and my best friend gave me a star map of the southern hemisphere for my birthday. Coincidentally she had started to do volunteer work at the observatory Mercurius in Dordrecht. During a holiday in the Netherlands we visited there and got a private tour. That stimulated us even more and we bought books about astronomy, watched all the documentaries and Corné bought his own telescope. Now we know quite a bit about it and, with our guests, we watch planets, star clusters and nebulas through our telescope. We even build a special deck from which we can watch the stars and called it Mercury, after the observatory Mercurius in the Netherlands where it all started. They even gave us a laser pen to point out the stars and constellations.

Regards from the bush
Miriam

Saturn, Lord of the rings

2011-07-03T00:40:00.000-07:00

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.
nine times farther from the Sun than Earth. With the naked eye it can be seen as a yellow/orange star. Now it is winter we have beautiful clear skies with thousands of stars, since we look at the centre of the

Regards from the bush
Miriam

introducing myself

2011-06-30T05:30:00.000-07:00

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
is never boring and in the past seven years we had some adventures, from elephants in our backyard to a cobra in the kitchen! For our adventures here in Africa read my blog Life in the African bush.

We were already interested in astronomy but here it became a hobby and we now have a ten inch telescope to look at the beautiful night sky.In this blog I want to share my passion for astronomy with you.

Bush regards,
Miriam