The Art of Observing

There is an art to observing the night sky. What is not immediately obvious is the time it takes to set up and prepare to maximise your chances of a quality experience. Binoculars are a very good start but eventually you will be drawn into telescopes. Beware, not all telescopes are born equal! There are different types. If you imagine a traditional telescope it will be a refractor. However, there are other types of telescopes which are reflectors, where light is collected by one mirror that reflects it onto a second mirror, then into an eyepiece.

If you want to observe planets, get a telescope that has a long focal length or a high focal ratio (f/10 will be stamped on it somewhere). This is called a ‘slow’ telescope. ‘Faster’ ones, better suited to fainter objects, have a lower focal ratio, eg f/5. An important first job after acquiring a telescope is to line-up your finder-scope so that it has the same view as your main telescope. This is best done during the day, by focusing on a distant object. This is really a key job and will save you a great deal of frustration later on, as trying to do this at night is ten times harder! Also choose the best nights for those very faint objects, when the Moon is not spoiling the show.

If your telescope is indoors it takes up to an hour to cool down when you take it outside. Any earlier and you may find the lens covered in mist or your view wavy from the warm air trapped inside. While that is cooling down, you will need to give your eyes a chance to adapt by using a torch with a red filter as you set things up. This may take about 20 minutes. In my opinion, at low power the best direction to view is the South because you have access to the planets. In general, don’t be tempted to use your most powerful eyepieces. Measure the diameter of the end of your telescope in mm (aperture) and don’t exceed more than double this in terms of magnification. There are many reasons for this but here are two very good ones. Unless you have paid a great deal of money for a quality telescope then the optics may not be good enough at high power. You may be able to tell its quality by seeing if the manufacturer has put a restriction (like a plate with a hole) inside the tube. If there is one there, then the quality of your optics may not be too good. Secondly, when you look through a telescope at high power it is very difficult to point it and find objects, even the biggest of objects (like the moon!). When you do have it in your sights then things very quickly drift out of view at this power.

When (not if!) you get hooked you will realise that you need to plan ahead. As your set-up becomes more complex you need to allow more time. Your tripod or mount may need to be aligned in a special way. You may need to heat your telescope to stop it freezing up. A tripod will only take you so far in this hobby until you will need a motorised mount. If you are controlling your telescope by computer, your exact location on the earth needs to be factored in. Then there is the software and cables…. the list goes on! There is something to be said for keeping it simple and just scanning the night sky. But after a while you will get drawn in by an irresistible force to seek out objects and try to image them. Try to resist if you want a simple life!

This hobby is not for the faint hearted and will test your patience and optimism, then burn a hole in your pocket. It will stretch your sanity and disappoint you relentlessly. But when it all comes together it gives you a massive sense of achievement and satisfaction that is hard to match.

What to look out for in March.

March 20th is when the night and day are almost exactly the same length, a new Moon appears on 24th and Summer time begins on the 29th. Early morning on the 31st looking SE you will see a clutch of planets; Saturn, Mars and Jupiter huddled together low on the horizon.

Hydra and the Ghost of Jupiter

The Night Sky February 2020

It sounds like a great title for a new Harry Potter book but I refer to Hydra, the largest constellation of all. Portions of it are visible from anywhere in the world. The most recognisable part of the constellation is its head; this is made up of a group of six stars. In mythology, it was the second of Hercules’s twelve labours to defeat the Hydra. The sea monster had the body of a snake with nine heads. When one was chopped off it just sprouted another 2 or 3! He managed to defeat it and the story is immortalised in the sky. Mid-month, looking south-east half-way up the night sky you will see Hydra’s head, just to the right of the inverted question mark that forms Leo. It is not until mid-March around midnight that the whole constellation becomes visible in its entirety. Located in the constellation of Hydra is an object that William Herschel discovered in 1785 and it is mysteriously named the ‘Ghost of Jupiter’. This object is a star that has thrown off its outer layer to produce a wonderful display called a planetary nebula. It is very faint, but at the centre is the remnant white dwarf star.

To look at it through a telescope, you will be reminded of the similar appearance and apparent size to the planet Jupiter, hence the name. Of course the nebula is much further away (1000 light years) so as you can imagine it is colossal, at 2 light years across!

Exoplanets

Back in 1991 we only knew of one solar system, ours! We looked out into space and only guessed that they existed elsewhere. No-one could have imagined that by 2020 that we would have discovered over 4000. What is even more remarkable is the way they are being discovered.

The transit method is measuring a small dip in the light of a star as an exoplanet passes in front. Another method is by detecting the ‘tug’ the planet makes on its parent star by measuring how this effects the star’s distance to us. Both of these methods are amazing in the sense that the measurements are so miniscule. It is also a demonstration of how ingenious astronomers can be in discovering something that seems impossible to do.

Exoplanets range in size and positions. Some are more massive than our own Jupiter, others are smaller than Earth. The orbits range from the parent star to very distant to incredibly close. Importantly, the range of distances from the parent sun where liquid water could exist on a rocky planet is called the habitable zone. Latest research shows that nearly a quarter of Sun-like stars have Earth-sized planets in their habitable zones. There has even been an exoplanet discovered that has its own exomoon!

So when you look out into the dark night sky this month, just pick any star and in all likelihood it will have planets orbiting it. You may pick one that has a planet in the habitable zone. The question it raises is how common is life out there?

Moon and planets this month.

The Full Moon this month is on 7th February (New Moon 23rd).

Between 18th-20th of this month you will get the chance to see Saturn, Jupiter and Mars just before sunrise, very low in the south-east. They will appear to be following the same path of the Moon over this period.

A very bright and brilliant Venus will be on show in the evening sky towards the end of the month looking West.

4 out of 9

The Night Sky January 2020

Lights out

Even if you are not ‘into’ astronomy most people connect to a clear moonless night. It is often a rare moment where we have chance to commune with nature. There is something primeval about it, like being transfixed watching an open fire. It would be a very sad day if the wonders of the night sky were taken from us by the glare of street lights or light pollution in general.

There is a scale to measure the night sky’s brightness called the Bortle scale. The nine level scale ranges from Class 9 (inner-city skies) through to Class 1 (the darkest available on Earth). It is estimated that one-third of humanity now cannot see the Milky Way and that this link with nature has been severed.

Here in Embsay we are lucky and enjoy around a Class 4 Bortle night sky, although if you are living under a new LED street light it may as well be Class 9! At least they go off around midnight (thank goodness.) Please keep the night sky dark by thinking carefully about external lighting. Not only can you save energy but you can also maintain the wonderful gift of our Embsay night sky for the next generation.

Can you see it?

An accepted key indicator of sky conditions is the ability to see a particular galaxy (M33) with your naked eye. The galaxy is called The Triangulum Galaxy and sits unsurprisingly in the triangular shaped constellation, Triangulum. M33 is easy to see with averted vision for a Class 3 sky, but is not possible for a Class 4 unless high in the sky. See if you can spot it. Try to look at it just off centre, to the side, rather than directly. This is called averted vision, which allows your eyes time to adapt to the darkness. On my diagram its location is due west for you to give it a go.

Also I’ve included an image taken from Embsay exactly a year ago, hugely magnified, as it will appear as a small smudge if you can spot it with your naked eye.

The best time to spot M33 will be around 24th January when there is a New Moon. (Full Moon 10th)

The Quadrantids

If you can’t sleep on the night of January 3rd to pre-dawn on the 4th, a clear sky should produce a spectacular meteor shower. The longer you wait for the Big Dipper to rise above the horizon the best chance you have to see the Quadrantids. A meteor per minute between 2- 3 am is the prediction, so good luck! Unlike many meteor showers, its peak activity lasts for less than a day so it is short and sweet but hopefully packed with fine bright streaks to maybe a fireball or two across the sky!

Planets

Later this month the early bird Mars is visible low in the south east in the morning, whereas Venus shines brightly in the south west in the early evening.