So far this year we have seen QVC presenters discussing whether the moon was a star or a planet. On having searched online a voice in their earpiece told them the moon is a natural satellite, however this did not solve their dilemma and seemed to just cause more confusion. With lots of different terminology and common misconceptions often held in relation to all things stellar, allow this article to clear up some real queries about the world and universe around us.
1. Planet Moon
Well, first of all, the moon is not a planet or a star. The Moon is a moon, which is a natural satellite of the Earth. Many of the other planets have also got moons, except their moons all have their own names. Like Jupiter’s moons, Io and Europa or Mars’ moons, Phobos and Deimos. A moon is object which orbits a planet, whereas a planet is a body which orbits a star. A satellite often refers to a man-made object placed into orbit around the Earth, whereas the Moon is a natural satellite. I hope this clears things up QVC but I’m sure you know this by now!
2. Day Moon
Sometimes another query also regarding the moon is the difference between the day moon and the night moon. There is only one moon and depending on what phase the moon is in will depend on what time of the day we see the moon. The moon takes 29.5 days to move around the Earth. One side is always illuminated by the Sun but dependent on where the Earth is located this can change what shape we see the moon, these are the moon phases. Before a full moon you can see the moon in the daytime sky in the afternoon, after a full moon it will be visible in the morning. (https://www.armaghplanet.com/blog/the-moon-in-the-daytime.html) .
3. Dangerous eclipses
Perhaps not such a fear or concern for most, however there are some theories about the dangers of solar eclipses. The next solar eclipse will happen on the 20th March 2015 and it will be a partial eclipse from here in Armagh meaning around 90% of the Sun will be obscured by the Moon. In ancient times, legends told stories that the sun was being swallowed or even stolen for that time. However some more modern strange myths suggest that pregnant women could be posing a risk to their unborn child of developing a cleft lip. This is not true. The only thing to pose a risk during an eclipse is looking at the Sun directly. The risk is magnified if you try to look at the Sun with binoculars or a telescope. Glasses or solar viewing kits can be used for safety.
4. Planets can only be seen through large telescopes
Using a telescope or even a good pair of binoculars can help view objects in the night sky in better detail. The rings of Saturn and the belts, bands and moons of Jupiter can be seen. However it is completely possible to see the planets without any optical aids. The ancient Greeks referred to the planets as the wandering stars, and Mercury, Venus, Mars, Jupiter and Saturn can all be seen with the naked eye. However beyond this you will need to use a telescope. Jupiter, Venus and Mars are all currently visible in the sky at the minute in the evening.
5. The Pole Star is the brightest star in the sky
This star is a permanent, steady feature in the sky for navigation in the Northern hemisphere all year long. However, this is not because it’s the brightest star in the sky, in fact it’s the 45th brightest star. The reason this star is special is because it is above the Earth’s North Pole so it always appear to be in the same part of the sky. However, wobbles in the Earth’s orbit will mean that Polaris will change…eventually. In the year 13727 our Pole Star will be the star Vega, in the constellation of Lyra. The actual brightest star in the night sky is Sirius located in the constellation of Canis Major. This star has a magnitude of -1.44, lower than any other star. (The lower the number the brighter the object).
6. The Plough (or Big Dipper) is a constellation
The familiar saucepan shape of the Plough is often one of the most recognised patterns in the night sky. The seven bright stars that make this pattern are not recognised as a constellation by themselves, instead they form part of the larger constellation of Ursa Major or the Great Bear. The Plough is an asterism, which is a familiar group of stars in the sky but not a constellation. Other examples of asterisms are Orion’s Belt, the Summer Triangle and the Great Square of Pegasus.
7. The Moon shines with its own light
The light from a full moon can shine so brightly it can wash out fainter objects in the night sky. It has inspired music. However the moon does not produce its own light. The only reason we see the light from the Moon is when the Sun’s light reflects off it and this is what we see. This is also the case with the planets. They also reflect the Sun’s light towards us. The moon is actually quite dark. The Apollo space suits worn by the astronauts on the moon were quite dirty by the end of the mission. The dark grey moon dust also was very abrasive on their suits causing parts to corrode. As the Sun, Moon and Earth move we see different parts of the moon illuminated, this is what causes the moon phases.
8. The Dark Side of the Moon
The somewhat elusive dark side of the moon has caused some conspiracy and unusual theories. From the Earth we only ever see one side of the Moon. However this is not really as mysterious as it first seems. Firstly, the entire Moon does see the Sun, no part of the moon is in darkness permanently, and the far side of the moon is a better way of describing it. The reason this happens is because the length of time it takes the Moon to orbit the Earth is the same length of time it the moon to complete one orbit on its axis. So therefore the same side of the Moon always faces the Earth. This is known as synchronous rotation or tidal locking.
9. There is no gravity in space
Often when talking about astronauts in space and training for a zero-g environment implies that there is no gravity in Space. However it is gravity which keeps the planets in orbit around the Sun and there is gravity everywhere in Space. In the Space Station the astronauts are experiencing 90% of the gravity that is on Earth. The reason that they are floating is because the Space Station is constantly falling and causing this weightless environment. Micro-Gravity is a better way of describing it.
10. Shooting stars are falling stars
Meteors are not actually stars at all but instead tiny pieces of debris from space perhaps about the size of a grain of rice burning up as they travel through the atmosphere. Much larger pieces of debris create bright fireballs in the sky and if the meteor is large enough it can fall land on the Earth as a meteorite. At certain times of the year the Earth moves into patches with more debris (left behind by a passing comet) than others creating beautiful meteors showers.
Video of Chelyabinsk meteor Feb 2013
(Article by Martina Redpath, Senior Education Support Officer)