The Night Sky for February, 2010

The highlight this month is the planet Mars. Easy to spot as a bright red object in the night sky, visible in the east at sunset, moving to the south at midnight, and heading further west in the morning hours. And, because both the Earth and Mars are on the same side of the solar system at the moment we are quite close to Mars, making Mars look brighter in the evening sky, and big when you look through a telescope.

This why there are some fantastic images of Mars being taken recently, including this one from local astro-photographer Pete Lawrence, showing a dust devil that has pasted across the martian south pole (more details at SpaceWeather.com).

By 10pm, the planet Saturn is also rising in the east. The rings of debris that surround this planet are visible through binoculars if you have good eyesight, or easily through a small telescope to the rest of us.

Orion (the hunter), Taurus (the bull) and Canis Major (the great dog) are the dominating constellations this month, with the bright star Sirius forming the nose (or sometimes the collar) of the dog. You should not miss out on looking at the Pleiades or the Orion Nebula through binoculars, and notice how Sirius twinkles due to our turbulent atmosphere.

To find these objects, I recommend that you use either Stellarium or SkyMaps.com.

Happy Solstice!

At 17:47 GMT today, it is officially winter!

That is the time when the poles of the Earth are aligned with the Sun, which is what we call the solstice. The North pole is now pointing away from the Sun (the Winter Solstice, and the shortest day), in the Southern hemisphere, the South pole is pointing towards the Sun (the Summer Solstice).

The image below shows a stacked series of images taken 20 minutes apart throughout the 17th December, 2005 (within just a couple of days of the winter solstice), showing how the Sun moved across the sky during that day, from the South-East to the South-West. A timelapse movie version is also available, showing how low the Sun is in the sky at this time of year.

There are lots of special events to mark the solstice, including a gathering at Stonehenge in Wiltshire (see these photographs: #1, #2, #3, #4). Under the early Julian Calendar, the winter solstice actually occurred on the 25th of December, but because that calendar was not accurate, the solstice slipped to the 21st (the accuracy of the calendar was corrected with the introduction of the Gregorian calendar in 1582).

However, we still traditionally keep the 25th of December as the day for celebration, and Christmas now includes a rich mix of celebrations, including Roman (Saturnalia, and Dies Natalis Solis Invicti, the birthday of the unconquered sun), Nordic Pagan festivals and the Christian celebration of the birth of Christ (see more about the origin of Christmas at this Wikipedia article).

Whichever way you choose to celebrate this time of year, we hope you will enjoy yourselves and have a very happy festive season!

December's Night Sky

This is the month to take advantage of, and enjoy, the long nights!

The earliest sunset here in Sussex occurs at 15:54 on the 12th of December, and the shortest day is on the 21^st this year. The Earth is tilted, and the shortest day occurs when that side of the Earth is tilted directly away from the Sun - and so the solstice actually occurs at a specific moment in time, at 17:46 on the 21^st December, 2009.

The increasingly inaccurately named summer-triangle is still visible, low in the west, but only until 7.30pm - ideal for after-school observing events! And the Andromeda galaxy is still well placed in the evening sky (see last months posting for full details about both of those).

Jupiter is still a wonderful sight until about 8pm throughout the month - just look for the brightest object you can find, low in the west, and that will be Jupiter! Look through binoculars or a small telescope to see four of the 60 moons that orbit this gas giant.

The 21^st of December is a great day for a photo' opportunity. That late afternoon and early evening, the planet Jupiter is visible just below the Moon. And just to the top-right of Jupiter, is the planet Neptune - although you will need a telescope to see Neptune, as it is 10,000 times fainter than Jupiter!

Rising at 8pm in the east is the constellation of Orion - a very familiar sight in the winter skies, thanks to the three stars that form a straight line, and which are known as Orion's belt (as in the photo to the left). Just below those three stars in a line, are another group of three stars in a line... only, the middle star is not a star at all, but a huge gas cloud where stars are in the process of forming. You can see it with your own eyes, but look through a telescope and you can see much more detail, and take a long exposure photo', and you can see even more detail! The movie below shows the difference between looking through a telescope yourself, and taking a 15 minute long exposure photograph.

You can get some very easy-to-use and clear star maps from either Skymaps.com, or by using the excellent (and free) Stellarium Planetarium software.

November's Night Sky

The sun is setting at around 5pm during November, so here is how to enjoy the long winter nights!

The highlight of the evening sky is the planet Jupiter, visible low in the south to south-west up until 10.30pm in the evening. Take a look at Jupiter with binoculars, or a small telescope, and see how many of Jupiter's Moons you can spot – just as Galileo did 400 years ago. You should be able to see up to four moons, and if you take another look just a few hours later, you may be able to notice that the moons have moved a bit in just that very short period of time.

The planets Uranus and Neptune are also visible in the evening sky, but they are just-too-faint to be seen with the unaided eye, which is why these two planets were not discovered until after the invention of the telescope.

Early in the evening, looking towards the west, you can still see the summer triangle of stars – Vega, Altair and Deneb – until about 9pm (see the chart to the right; click on it to see it full size). Within the triangle, you can see the remains of two dead stars using a telescope – the ring and dumbbell nebulae. There is also a beautiful double star called Albireo within the triangle.

This is also a great time of year to see the Andromeda galaxy – the most distant object that you can see with your own eyes! It may be 2.25 million light-years away, but it is quite easy to find. Just go somewhere dark, away from the light pollution and inefficient lighting of our towns and cities, and look for the square of Pegasus. The square can be found by looking towards the South, about half way up the sky. It’s quite a big square – just bigger than your hand at arms length. Look towards the star that makes the top-left corner of the square, then follow two bright-ish stars up towards the top left, and then follow two more slightly fainter stars towards the top right (as in the map, right), and just there is the Andromeda galaxy! The W-shaped constellation of Cassiopeia also usefully “points” towards the galaxy.

And it is huge! It is actually six times the diameter of the full Moon, but it appears faint because it is so far away, and so with our own eyes we can only see the bright centre of this massive city-of-stars. For the best view, take a look through binoculars (telescopes usually have too high a magnification for you to see this galaxy clearly).

Now look to the left of the square of Pegasus, about 4 times its size, and you will see a bright red giant star called Aldebaran. Just to the top-right of Aldebaran, you’ll be able to see the Pleiades star cluster, also know as the seven sisters because you can see up to seven stars with your own eyes (pictured left as a wide-angle view, and right as a close-up photograph). This cluster is a beautiful sight through binoculars, where you can see up to 50 stars. Again, don’t use a telescope, since you will only be able to see one or two stars at a time – low magnification is what you need for a cluster that appears bigger than the Moon in the night sky.

You can get some very easy-to-use and clear star maps from either skymaps.com, or by using the excellent (and free) Stellarium Planetarium software.