To coincide with three days of BBC Stargazing the National Museum Cardiff will be hosting a free fun day of activities, talks and displays on Saturday, 11 January between 10am-4pm.

Budding young astronomers will be able to find out what it was like to look through Galileo and Newton’s early telescopes, and how today’s high-tech telescopes compare.

Ever wondered how new planets are discovered? Learn how astronomers explore the sky at multiple wavelengths using the Herschel and Planck space telescopes.

There will be also an opportunity to hear two space talks. At 12pm Dr Chris North discusses the 'Mysteries of the Solar System'.

Then at 2pm Professor Mike Edmunds discusses the 'Expanding the Universe - Copernicus, Kepler, Galileo and Newton'.

In the meantime there's plenty to do on the BBC Stargazing website including 2014 Stargazing events, galleries, star guides and video clips to watch.

We also have a BBC Wales Flickr group dedicated to the Dark Skies reserve recently created over the Brecon Beacons National Park that you can add your celestial images to.

Sunset from the Great Orme with Penmaenmawr & Anglesey in the distance. Image by Glyn Roberts, Conwy.

Today is the last day of the fine, sunny weather. Tomorrow will be much cloudier and it will turn milder by Wednesday with south-westerly winds bringing some rain and drizzle. Top temperatures on Wednesday 10 to 12 Celsius.

On Thursday rain will clear and it will turn colder and brighter again. Windy too with wintry showers. The showers falling as sleet and hail. Some snow is likely too but not much. Most of it on higher ground and on the hills and mountains.

Don't forget, there is another episode of Weatherman Walking tonight on BBC One Wales at 7.30pm

Meanwhile Stargazing Live starts tonight at 8.30pm on BBC Two so you've time for a cuppa in between!

Conditions tonight will be ideal for looking at the night sky but it will be a different story tomorrow night and on Wednesday night with much more cloud expected.

Dr Huw Bolton, Conservator - Geology at the National Museum Wales.

Again this year, the National Museum Cardiff will be running a wide range of astronomical events, activities and talks to tie in with the BBC Two programmes.

Winter is a great time to explore the night sky. The long nights mean that you don't have to stay up too late to do a bit of stargazing.

The constellations visible at this time of year are some of the brightest in the sky, and in early 2012 two bright planets are well placed for viewing.

Jupiter and Venus are in the evening skies this winter and spring, and give an excellent opportunity to tread in the footsteps of Galileo in the winter of 1609-10.

He was the first to see Jupiter's four bright moons orbiting around the planet, and the first to see the phases of Venus - observations that changed humanity's view of the Universe.

Soon after the Sun sets, Venus can be seen shining brilliantly white in the south western sky. It will become ever better placed for observation over the coming months as it moves closer to Earth and develops its spectacular crescent phase.

Jupiter shines pale yellow in the south after sunset, making an interesting naked-eye colour contrast with Venus, reflecting (literally) the different compositions of their cloudy atmospheres.

Jupiter's moons and the crescent of Venus can nowadays be seen using simple binoculars. Our activities at the Museum will include a working model of Galileo's telescope.

You will be able to see for yourself just how difficult it was to make these remarkable observations 402 years ago, and see how far telescope technology has advanced since then.

By 8pm on these winter nights, the bright winter constellations start to dominate the eastern sky: Orion, Taurus, Gemini and others. The best known pattern is that of Orion with its distinctive hourglass shape. There are many myths surrounding Orion.

This star pattern was seen as a great hunter in Greek mythology, and was placed in the sky far away from his venomous nemesis - the constellation Scorpius.

Many of the stars in Orion lie at a similar distance, and are of a similar age, as they formed close together in the 'Orion arm' of our spiral Galaxy.

The main stars of Orion itself are white in colour and are therefore extremely hot - with the exception of the spectacular red giant Betelgeuse, which is much cooler, but over a thousand times the diameter of the Sun.

The contrast between the colour of Betelgeuse and the rest of Orion's bright stars can be seen with the naked eye.

Below the three stars of Orion's Belt lies the great Orion Nebula. This is a 'stellar nursery', where stars are being born out of vast clouds of hydrogen gas.

This nebula can be easily seen through binoculars as a glowing greenish patch of light, one of several bright deep-sky objects visible in binoculars at this time of year.

While seeking out this nebula, look also for the spectacular Pleiades star cluster in neighbouring Taurus. The three stars of Orion's Belt point upwards and to the right, straight towards the Pleiades.

Also known as the Seven Sisters of folklore, the Pleiades are one of the great sights of the winter sky.

Moving closer to home, Earth impacts have been in the news recently with the likely crash of the Russian Phobos-Grunt space probe after it failed to leave Earth's orbit.

Broken space probes are not the only hazard to threaten Earth from space - as part of our activities, the museum will be running an impact simulator, so you can see the disastrous effects that a comet or asteroid would have if it hit the Earth.

Smaller meteorites are much more common (and less dangerous) and have certainly landed in Wales in the past, as I have mentioned in my previous blog entry.

If you have found what you think might be a meteorite, bring it along to the museum on the day and we will identify it for you.

So if you want to know more about space and stargazing, come along and speak to us. Take a look through our telescopes, hear talks by professional astronomers, see how the ancients saw the constellations, view our meteorite collections and much more.

Events in Wales:

The National Museum Cardiff will be hosting Star Attractions at the Museum all day Saturday 21st January 2012.

The National Waterfront Museum, Swansea, will be hosting a Star Party on the evening of Friday 20th January. All entry and events are free.

You can also join in with the live programme via Twitter #bbcstargazing.

Check out the How to Guides for star and Moon guides, planetary activity and audio guides, videos and more.

Dr Huw Bolton

In January, the BBC's Stargazing LIVE will link astronomers - both amateur and professional from around the world in a three-day event.

There are also plenty of other many activities being organized by local astronomical societies and the National Museum of Wales, so everybody can join in.

• So what is astronomy all about?

It is the oldest of the physical sciences and involves the study of the Sun, Moon, planets, stars, galaxies and most fundamentally of all, how we attempt to answer the biggest questions in Nature - the origin and structure of the Universe itself.

Whether you are a stargazer, a serious astronomer, or someone who just wants to know more about the Cosmos, astronomy is an outdoor pursuit which you can do from your back garden, with no more elaborate equipment than the naked eye.

Even if you are not able to get out and see the stars, the ideas and vistas revealed by astronomy hold extraordinary fascination.

Astronomy in Wales has a long history that extends way back over the centuries. There have been a number of pioneers in astronomy in the Principality, and in 1609, whilst Galileo was making his Earth-shaking observations through the newly-invented telescope in Italy.

Meanwhile here in Britain, Thomas Harriott in London and his friend William Lower in Carmarthenshire, Wales also acquired telescopes which they used to observe the Moon.

During the 1850s John Dillwyn Llewelyn and his daughter Thereza made some of the earliest photographs of the Moon from their private observatory at Penllergaer near Swansea.

In 1888 Isaac Roberts of Denbighshire took the first photographs of the famous Andromeda Galaxy, revealing detail of its spiral structure never seen before.

This galaxy is visible to the naked eye, and can be seen as a faint misty patch high in the southern sky on autumn and winter nights and is 2.5 million light years away from our Solar System.

The recent solar eclipse captured by Kev Lewis at South Stack, Anglesey on 5 January 2011.

It was called the 'Little Cloud' by the 10th Century Persian astronomer Al Sufi, and is the most distant object visible to normal unaided eyesight.

Its faint glow is the combined output of the billions of stars that make up this giant galaxy. If you have a pair of binoculars, they will give you a great view of this magnificent object.

Closer to home, Wales has also received visitors from our own Solar System, not aliens unfortunately, but meteorites - rocky remnants left over from its formation. Famous meteorite falls occurred at Pontlyfni in 1931 and at Beddgelert in 1949 - when the meteorite landed on a hotel.

• So how can you get involved in astronomy?

Firstly, owning a telescope is not a necessity for viewing the night sky. Binoculars are excellent instruments for viewing the skies, and will reveal far more than can be seen with the eye.

The UK, including Wales, is lucky in having large numbers of flourishing local astronomical societies, many of which hold public viewing sessions where you can talk to enthusiasts, ask questions, and have the opportunity to use telescopes.

Wales, at the moment, is also lucky in that large parts of the nation are still relatively free of artificial lights - the careless use of which blots out the stars making them difficult to see from cities, and increasingly, many smaller towns. Large parts of the country are still free of light pollution however, especially our National Parks.

If you want to know more about astronomy, how to take part, what to look for, how to use a telescope (or anything else), follow the BBC's Stargazing Live event, and come along to one or more of the free events being held across Wales to celebrate the night sky.

At any event, there will be a wide range of people with different levels of experience, so don't feel shy about asking questions.

Dr Huw Boulton

National Museum of Wales: See for yourself how these early telescopes worked, and see part of the Beddgelert Meteorite and other meteorites from around the world at the National Museum Cardiff on 8th January 2011 and 2nd April 2011.