Posted on behalf of Conor Farrell

 

We had some great sights in the sky in 2012, but 2013 is expected to be better: we’re going to have northern lights, planets, meteor showers, and maybe even two of the most spectacular comets you will ever see in your life!

comet_mcnaught_voyagernz_CC http://www.flickr.com/photos/voyagernz/5750491406/in/photostream

McNaught comet taken by voyagernz (CC-BY-ND)

Jupiter is a bright planet at the moment, and was beautifully placed right next to the Moon on the evening of Christmas Day. You can see this happen again soon on February 17th.

Jupiter was at ‘opposition’ last in 2012, meaning that it was in the exact opposite side of the sky to the Sun. The planet will change position in the sky quite slowly, so it will remain an extremely bright object towards the south and south-east for the start of 2013.

Spotting a planet can be tricky at first, but with a few tips you’ll be able to start picking out the planets: While stars can twinkle in unstill air, planets don’t twinkle at all; Jupiter is the biggest planet, so always appears rather bright; Mars can be close and bright (but sometimes more distant and faint), and will also have an reddish tinge to it; Venus is always extremely bright, and because it is closer to the Sun than Earth, it always appears somewhat ‘close’ to the Sun: this means that it will only be spotted with the naked eye around sunrise or sunset.

Jupiter looks great without any help, but if you have a pair of binoculars or even a small telescope you’ll get to see its four largest moons. These are the Galilean moons, discovered by Galileo over 400 years ago: Io, Europa, Ganymede, and Callisto (lovers of Zeus, the Greek name for the god Jupiter). If you take a look once every couple of hours (or even every couple of nights) you’ll see that the moons change position, because they are in orbit around the planet.

At the moment, when you spot Jupiter, you should be able to find two star clusters nearby: below it is the Hyades Cluster, the nearest star cluster to our own Solar System. You can recognise the Hyades as group of somewhat fainter stars in a V-shape. Above Jupiter is another – more distant but brighter – cluster called the Pleiades, or the Seven Sisters. These objects can be found with the naked eye, but viewing through a telescope will reveal that there are hundreds of stars in the clusters, not just the few stars that we can see with our eyes.

The Sun is approaching the peak in its 11-year cycle, meaning that it is expected to produce more and more sunspots. As a result of the magnetic fields associated with the sunspots, the Sun can ‘shoot’ out clouds of plasma, called coronal mass ejections (CMEs), into space. If one of these CMEs is directed towards Earth and interacts properly with our planet’s magnetic field, it can trigger a display of an aurora or Northern Lights!

Northern Lights (and Southern Lights) are usually concentrated near the poles, within the Arctic and Antarctic Circles. However, a particularly strong ejection from the Sun can result in a display visible as far south as Ireland, or further! In fact, we saw several such displays occur last year which were visible from Ireland.

The best place to see the Northern Lights is in any dark location (even only a few kilometres outside any town in Ireland) that has a clear northern horizon. The further north you are, the better chance you have of seeing an aurora. Unfortunately, the aurorae are rather unpredictable and occur at very short notice: we can tell if a CME will strike Earth with a couple of days notice, usually, but we won’t know if the magnetic fields will interact properly until often only a few hours before a display starts. However, an auroral display can potentially last for several hours – sometimes all night – so keep an eye out online and on the news for any reports that an aurora is on the way!

The best meteor showers take place later on in the year. However, on each occasion the Moon will be quite bright and may prevent some of the fainter meteors being seen. That said, meteor showers can also produce fireballs: fast-moving and extremely bright meteors that are often seen to break up during their rapid descent through the upper atmosphere. The bigger fireballs (ones that are brighter than the Full Moon, as a general rule of thumb) can sometimes survive the fall to the surface, meaning that meteorite fragments may be found!

A meteor is caused by a fragment of debris – called a meteoroid – that enters Earth’s upper atmosphere. Due to friction, they become surrounded in a glowing plasma in a region 70-100km above the ground, resulting in the bright streak we see. If they don’t burn out in this region, they slow down due to the increase in air pressure as they descend, and fade out or break up. This happens at approximately 50-80km altitude.

Meteors can appear closer or larger than they actually are, and it’s quite common to think that a fireball has landed closeby. This is a trick of the eye and the brain. It’s extremely hard to tell the distance of a meteor because your brain has no way of knowing how long the streak is: is it one metre long? Or is it ten kilometres long? Without knowing this information, it’s not possible to tell how far away a meteor is by using your eyes alone.

The meteor showers in question are the Orionids, Leonids, and Geminids, occurring in October, November, and December, respectively. The showers last several days or weeks, but will peak on a particular night when you are most likely to see more. There is no particular direction to look in as meteors can appear anywhere in the sky, and you will not need any special equipment to see them; just use your eyes! The dates of the peaks are listed below, going from the night of one day into the morning of the next. Meteors showers are best observed between midnight and dawn.

https://www.flickr.com/photos/walkadog/3389058334/

Aurora Borealis taken by Joshua Strang (CC-BY)

But all those beautiful and stunning sights are small fry compared to what astronomers are hoping to see in March and December: assuming they don’t evaporate or disintegrate – which is a distinct possibility – the best astronomical sights of the year will be two “Great Comets”.

While there is no official definition of the term, a Great Comet is a comet that becomes exceptionally bright and bright enough to be noticed by the casual observer. The Great Comet of 1997 is one you may remember: known as Hale-Bopp, this object became bright enough to be seen with the naked eye early in 1997, and grew brighter and brighter and dominated the northern sky for months.

The first of the Great Comets of 2013 is expected to appear in mid-March, right on time for St Patrick’s Day. This was discovered using the PANSTARRS 1 telescope in Hawaii and so is named Comet PANSTARRS. While this comet will be a breathtaking sight, it is the November and December appearance of a comet – just in time for Christmas – that will capture the attention of the world.

The second one of 2013, Comet ISON (named after the International Scientific Optical Network), is a special kind of comet called a sungrazer. All comets orbit the Sun, but sungrazers pass extremely close to the star; in many cases the comet evaporates and is destroyed. While many comets make the trip from the outer Solar System to the Sun several times, sungrazers often just make a single, one-way trip to their destruction. Assuming ISON doesn’t fizzle away during its close approach to the Sun, we may be treated to a spectacle 15 times brighter than a Full Moon with a vast tail, making it easily visible in broad daylight – something that hasn’t been seen since the Great Comet of 1680.

But whatever you do, by far the best way to enjoy the night sky is to simply go outside and be underneath it. Wrap up warm, make a flask of a hot drink, and go outside where it’s dark with as little interference from lights as possible. If possible, lie back on a sun lounger (it’ll stop your neck hurting, and you’ll see much more of the sky at once), and bring even a small pair of binoculars if you have any.

Let your eyes adjust to the dark for around 10 minutes or so, and don’t look at any lights – including your phone! You’ll see more and more fainter stars pop out of the dark background and before long you should be able to make out the Milky Way stretching across the sky. You’ll also spot some star clusters, vast nebulae, and even other galaxies! Lie back, relax, and enjoy the sights.

Astronomy Dates for Your Diary

  • January – May: Jupiter in the sky

  • March: Comet PANSTARRS

  • April/May: Best time to view Saturn in the east and south-east

  • May 28: Venus and Jupiter placed next to each other just after sunset in the west

  • October 21/22: Orionid Meteor Shower

  • November: Comet ISON

  • November 1718: Leonid Meteor Shower

  • December 13/14: Geminid Meteor Shower

  • December: Mars gets brighter in the skies, and will be at its brightest and closest to Earth in April 2014