RECOMMENDED OBSERVING TARGETS

INTRODUCTION

Jupiter

Everybody in astronomy knows that this king (or queen) of planets is a wonderful sight, offering a large and detailed surface for observation. Presenting a deceptively warm looking sphere, it is particularly impressive around opposition, when it is at its closest to us at 365 million miles, revealing two wide equatorial belts and darkening at its poles in even a small telescope. 

Oppositions occur every one year and one month; I have listed some below:

2023 - 3rd November

2024 - 7th December

2026 - 10th January

2027 - 10th February

2028 - 12th March

In larger telescopes, Jupiter reveals glorious detail - whirls and festoons in the equatorial clouds and a number of other, narrower cloud belts and various shades of yellow and brown on different areas of the `surface'.

From year to year, the appearance of the belts tends to vary, as gaseous eruptions occur on the planet. I love the curvature that can be seen on the gaseous surface, as well, really giving the planet a 3-D appearance. This curvature is particularly marked if the planet is observed in twilight conditions, rather than the full darkness that reveals most detail in the belts and the red spot region. In my opinion, there is value in both twilight and dark observations, each giving a different experience.

Jupiter is a fairly low contrast object, so it does not always take magnification well, softening in appearance as the magnification rises. This particularly affects smaller telescopes. The 14 inch manages well, usually allowing a good quality image at 275x to 330x. I can sometimes even manage to view it clearly at around 400x, a magnification that allows ample detail to be seen, with very comfortable viewing.

  Jupiter, as seen through a six inch telescope

I find that a little more detail can sometimes be teased out of the telescopic image of Jupiter using my Skywatcher Light Pollution Reduction (LPR) filter (a broadband filter that enhances red objects), or a blue Wratten #80A filter to improve the dark belt detail, white belt detail is enhanced with a Green Wratten #56 filter.

The LPR filter is also helpful in enhancing the Great Red Spot, which is visible in telescopes of 6 inch or larger aperture and, of course, is only visible if it is on the earthward side of the planet! Note, the planet turns through a full 360 degrees every 10 hours, so the view is variable in detail from night to night. The red spot is quite faint and actually seems to be salmon pink in colour, nestled in a surrounding white area of the Southern Equatorial Belt.

Four bright, pearl-like moons can be seen orbiting Jupiter, even with a small telescope. These moons are the famous Galilean moons, Io, Europa, Ganymede and Callisto. If only three moons are seen, it means that one of the moons is behind the planet, or possibly in front of it. 

These moons orbit the planet surprisingly rapidly, meaning that over the course of a typical two hour observing session position changes can be noticed for the innermost moon, Io. It is wonderful when one emerges from behind the planet during the course of an observing session. What is even more wonderful is when one of the moons passes in front of Jupiter and produces a transitory inky black spot on the planet's surface - a regularly occurring but spellbinding sight!

Saturn

I think that most people are struck with a sense of awe never to be forgotten when they first see Saturn through a telescope. It's a planet that is rewarding even in a small telescope, revealing ice-sharp looking rings and at least one moon. Again, a broadband filter can sometimes reveal a little more of certain, specific details, but I prefer an unfiltered view of this planet. 

Appearing much smaller than Jupiter, Saturn is nevertheless a breathtaking object in a larger telescope, revealing several moons and a ring system with its Cassini Division, Enke Minima and, on a good night, even the faint Crepe Ring. The planet often throws a sharp edged shadow upon the ring system, a 3-D enhancing sight to behold! 

Saturn takes magnification well, being a high contrast object; I have used a magnification of 550x successfully with the 14 inch, on nights of good `seeing'! At this magnification, the ring system is magnificent - amazing, considering that it is only around 30 metres thick in some places! 

Over the years, the ring tilt angle presented to us varies; about every 15 years the rings become edge-on to us, denying us the fascinating intricacy of their detail, but giving us an unusual view of the planet.

If you have a larger telescope (12 inch upwards) and the north pole of the planet is favourably pointing towards us, you may see that the pole is wearing what looks like a small grey Jewish skullcap, maybe 10,000 miles in diameter! This grey hat is a cloud system, bizarrely hexagonal in shape and is fittingly known as The Hexagon.  A green Wratten #56 filter enhances the greyness at the north pole, as well as the belts.

Saturn obligingly reaches opposition approximately every twelve and a half months, as detailed below:

2023 - 27th August

2024 - 7th September

2025 - 21st September

2026 - 4th October

2027 - 17th October

2028 - 30th October

Mars

Mars is a rewarding object when it is approaching, at, or not too far beyond opposition. Unfortunately, this only occurs for a period of about three months and then there's a wait of approximately two years for the next opportunity. When the planet is further away from opposition, it is a surprisingly disappointing small red blaze, devoid of detail and even challenging clear focusing at times! 

Around opposition, a good quality telescope of about four inches aperture will reveal dark features (Syrtis Major & Mare Tyrrhenum) on its surface. Syrtis Major is subject to seasonal changes.  At least one polar ice cap should be visible through such a telescope, as well, depending upon its position relative to the Earth's. Frosting can sometimes be seen on other parts of the planet, like the Hellas Basin, with larger aperture telescopes like my 14". 

Oppositions occur about every two years and one month, though the time intervals between them vary a little, so observing Mars clearly is somewhat opportunistic. In addition, the distance between Mars and Earth varies for each opposition, the closest distance being about 34 million miles at perihelic oppositions. Our most recent perihelic opposition was in 2003, the next  one being in 2018. However, Mars displays its features attractively for any opposition.

Some oppositions are listed below:

2025 - 16th January

2027 - 19th February

2029 - 25th March

Plenty of magnification is best with Mars - at least 200x - as it is a small object, being about half the size of Earth. A broadband filter is useful to enhance its appearance. Less subtle enhancement of certain features is possible with colour filters; I have found that an orange Wratten #21 filter will enhance both the contrast of Syrtis Major and the polar cap boundaries, and  a #58 (green) Wratten filter will enhance the polar detail.  An #80A Wratten filter (blue) is also generally effective on Mars.

Dark banding can sometimes be spotted at the edges of the polar caps of Mars, especially if a dark green Wratten #58 filter is used. These are called `Lowell Bands'

It should be borne in mind when observing Mars that the planet has a rotation period that is about an hour slower than our Earth day. On one `side' of the planet, there is a large area which is fairly featureless. For this reason, the view can occasionally  disappoint even during opposition. In the event of this featureless area dominating the view, it is just a matter of waiting for about a week for the planet to rotate significantly relative to Earth's rotation.

Mars has two moons, Phobos and Deimos, both of which appear very small through a telescope. They seem to be visible in telescopes of about 10 inches upwards, but are not always very easy to see due to the glare from the red planet. Hence, it's usually the case that just the outermost moon, Deimos, is visible, even though it's the smaller of the two. 

Mercury

Being nearer than us to the sun, the most noticeable and interesting thing about Mercury is that it displays phases, like the Moon. It is `full' at superior conjunction (opposite side of the sun to us)  and `new' at inferior conjunction (between us and the sun at its closest distance of 28 million miles). 

No detail is observable with normal amateur telescopes on the bright surface of this little planet.

Due to its proximity to the sun, the baked yet soft looking disc of Mercury is an elusive horizon peeper and, hence, is only  seen when around its greatest elongation. It is only ever visible low in the west, just after sunset, or low in the east, just before sunrise. 

Despite being a baked, searingly hot, rocky planet, it looks surprisingly soft and buttery through a telescope. Quite beautiful. Using a Wratten #80A  filter (light blue) helps sharpen the image of this planet, as does a #21 (orange) or a #15 (dark yellow).

Venus 

Venus, our nearest planet when at opposition, is seen much more readily than Mercury, being visible as a low elevation and unnaturally bright object for many successive months. The Goddess of Love is, in fact, the brightest object in the sky, apart from the Sun and the Moon. Hence, it is best observed through a telescope in twilight conditions.  It is also higher in the sky at this time.

It generally appears featureless, yet it is a rewarding target as it displays phases. When it makes its first appearance in the evening, it will look gibbous, as it is the other side of the sun to us. It will gradually approach the half phase over the coming months, which is how it appears when at western elongation. It then gradually changes to a crescent as it approaches its nearest point to the earth at 38 million miles distance.

After this, the opposite movement occurs as it slowly recedes from us, now visible in the morning.

When Venus is gibbous or at half-phase, there is an exciting chance of seeing cloud detail if colour filters are used. Useful filters are Wratten #47 (violet), #80A (light blue), #58A (dark green) and #15 (dark yellow).  However, high magnification will be required, 250x and above.

When Venus is a crescent, it is also entertaining to observe because sometimes very fine cusp extensions can be seen. Also bright regions at the ends of the cusps, called cusp-caps, are sometimes visible. The #58 filter can enhance these.

Uranus and Neptune

These two ice-blue planets can be quite tricky to find, as they blend in with the star background. Any surface detail that they might show is veiled from us by great distance, but at least these planets can be resolved into small discs if a magnification of at least 250x is used. They appear as hauntingly beautiful shades of pale blue. 

There is also the `thrill of the catch' in spotting them!

The Moon

Despite suffering the indignity of being maligned by most astronomers for its `light pollution' of their dark skies, this maddener of people is an excellent viewing target, being only a quarter of a million miles away. It reveals so much when magnified by a telescope, or even a humble pair of binoculars. 

Novae & Supernovae

For relatively rarely observable phenomenae, we have been treated recently, so I'm including these in the observing list. 

A nova, or supernova, appears to be a very bright new star that is often at a great distance, but it is actually the result of a large star imploding as it reaches the end of its life and is no longer able to sustain the outward thrust of its internal nuclear fusion which fends off the squeeze of its heavy gravitational pull.

Novae and supernovae are actually the same phenomenon, but given the prefix `super' according to the size of the explosion. They may be millions, or even billions, of times brighter than our sun.

I have seen three of these recently, using my 14 inch telescope:

(1)     August 2013 - Delphinus Nova. This was about magnitude 5, viewable in binoculars, at an estimated distance of about 13,000 LY.

(2)    January 2014 - 2014J.  I actually saw this one on the very night that it was officially reported, when it shone at magnitude 12 from within one of our local galaxies, M82, the Cigar Galaxy, which is about 11 million LY distant from us.

(3)    December 2014 - ASASSN-14lp. This was within distant galaxy NGC 4666, in Virgo. This was around magnitude 11, despite being around 80 million LY from us.

Although these are only seen as points of light, there is a thrill in seeing them, considering what they are!

STARS

The term Deep Sky Object is not inclusive of individual stars, as a star is only seen as a point of light, however high we crank the magnification (optical quality withstanding!). Many stars make good observing objects in themselves, however, by virtue of their colours and in the context of their close companions, a fact that is sometimes overlooked by observers.

Notable Stars and Asterisms

These stars are notable either because of attributes like deep, beautiful colour, or because they make up part of a significant asterism. This list does not include double, or multiple stars, which are detailed in the next table.

For asterisms, smaller telescopes, or binoculars, are generally best, with their wider fields of view. For individual stars, the colours are rendered richer and deeper in larger telescopes.

Double/Multiple Stars

Some stars have a close companion, or companions. When this happens, the term double, triple or even multiple is applicable.

There are many such stars displayed in the sky, seen as very close neighbours but varying in their separation. Some of them are multiple groups, but these are rare. I only know of two instances where more than three stars can be seen together by an amateur telescope, and these are:

(1) Sigma Orionis (a quintuple!), where four of its stars can be seen using a larger aperture instrument.

(2) Epsilon Lyra, appearing as a double, but where each component can also be split into a double.

When stars appear as doubles or multiples, it's either because they are actually close together or because they appear to be together from our viewing location. If they are actually physically close together, they are known as binary systems or, for three stars, trinary or ternary systems; if they just appear close together, they are known as optical doubles or optical triples.

I have listed the most attractive doubles and multiples in the document below.

Brightest Stars List

This is the top 25 magnitude ranking table of stars: