Our Solar System, the Planets and When's Best to See Them (updated May 2023)

Our Solar System comprises 8 official planets and Pluto, which should be a proper planet but was demoted by the IAU in August 2006. Also in our Solar System are 556,000-ish comets, asteroids and other planets' moons. The planets are, of course, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto.

 inner rocky planets  scaled out to Jupiter & Saturn  further scaled out to Uranus and Neptune
3 Different-Scaled Views of the Solar System looking "down" from above the Ecliptic (positions as of early Feb 2020)



In common with our Moon, the planets provide essential viewing for amateur astronomers even from places of bad light pollution. However, unlike most celestial objects, they do not appear in the same places in the sky at the same times of year. They move around. The word "planet" derives from the Greek Planetes, which means 'wanderer'.

The following paragraphs and charts are guides as to the best times for the near future to observe them. They are charted, over the next one-two years, as follows:

- Mercury - charted altitude when the Sun is 3 degrees below the horizon, which is roughly when it should start to become visible to the naked eye.
- Venus - charted altitude at the moment of sunset. Any later, she's too bright to view without being too dazzling to tease out any detail that might be available.
- The Others - charted altitude 2 hours after sunset, 2 hours being more-or-less the time it takes after sunset to become astronomically dark at the latitudes of the NH and SH sites chosen (London, and Sydney).

Mercury (updated May 2023)

Mercury is the closest planet to the Sun, the distance of its orbit from the Sun varying between a third and a half of Earth’s, meaning its maximum apparent distance from the Sun is never more than about 23 degrees of arc across the sky (about the distance between your outstretched little-finger tip and thumb-tip at arm's length) and mostly much less. Because the immediate “movement” of the Sun during the day (and that of any other Celestial object including the Planets) is overwhelmingly due to the Earth’s rotation, not the object’s own movement, Mercury is basically following (or preceding) the Sun down, and there is never much time between Sun-set and "Mercury-set". Luckily, when fully illuminated, Mercury's brightness approaches that of the brightest star in the sky, at around magnitude -1. (Sirius, the actual brightest star, has magnitude -1.46). But Mercury, even at only 50% phase, i.e. "D"-shaped, has a magnitude of about 0, the same as Vega, which is the definitive 0-magnitude star.

Consequently, the only realistic time to see Mercury is shortly after the Sun has set during twilight, and when it’s at “maximum elongation”, i.e. thrown out as far sideways in its orbit around the Sun from the viewpoint of an earthly observer. Furthermore, when it is at maximum elongation, the geometry of the situation means that it’ll be approximately 50% illuminated, and waning (getting less). The charts below show, for now and the near future, the altitude of Mercury each day when the Sun is 3 degrees below the horizon. They also show, in light blue on a scale from 0 to 1 (0% to 100%) the phase of Mercury, i.e. how much of a crescent or "full disc" it appears. Even seasoned astronomers get excited about seeing Mercury.

For an observer at 51 degrees N (e.g. London):

In the Northern Hemisphere, for the time being, Mercury only becomes realistically visible after sunset once per year, in Spring, where it rises to around 15 degrees elevation by the time the Sun is 3 degrees below. It was very easily visible in the second half of April 2023 just after sunset, and will be again the last half of March 2024. In the days immediately following, although the altitude will still be high enough, because Mercury is swinging around in its Solar orbit towards us and in front of the Sun, it's getting less and less illuminated, its phase waning into a diminishing crescent fingernail, losing visibility and brightness. Although that makes it more difficult to see with the naked eye, through a telescope Mercury’s crescent is a lovely sight. The same applies to Venus, actually.

One year's pattern roughly repeats itself from a current year to the next, with the relevant events happening around a fortnight earlier each year.


For an observer at 33 degrees S (Sydney or Capetown):

From the Southern Hemisphere, at its best, it's somewhat better. Mercury gets much higher for the same "3 degrees down" of the Sun, more than 20 degrees up in late summer and at least as good as Northern Europe again later in the year. It's best of all around early August 2023 and decent again towards the end of December 2023.

Similarly to the Northern Hemisphere, the pattern more or less repeats every year.

Venus (updated May 2023)

Like Mercury, Venus’ orbit is inside that of Earth. Which means that she too follows the Sun down at Sunset when she’s that side of her orbit, and she precedes the Sun at Sunrise when on the other side of the Sun. Thus, being the first “star” to be visible as twilight beckons on account of her extreme brightness, Venus is often known as the Evening Star or the Morning Star, depending on which side of the Sun she is in her orbit.

In fact she’s so extremely bright, magnitude -4 and therefore easily the brightest non-Sun object in the sky when she’s up, that she’s perfectly visible during the day as well. I actually prefer to view her in daytime because only then is she not dazzling in a telescope, and it's a nice party trick for the non-initiated.

You likely won’t have noticed Venus during the day as she’s a tiny bright speck in an otherwise bright blue sky. To see her through binoculars, you do need to “hunt around” in the right area until you see the bright dot. Ironically, with a telescope it’s easier. Use an App to find the approximate altitude of Venus for the moment, and using a digital inclinometer, set the angle of the telescope to that angle. Then point the scope in roughly the right direction and scan from side to side. You’ll find her quickly.

Observing Venus in darkness can be frustrating, because if there’s even a little turbulence in the atmosphere, called “bad seeing”, she will twinkle to the naked eye and the view through a telescope will produce enough sparkle and glare that you can’t really make out her shape.

Venus 2023-2024

Northern Hemisphere

For those of us in the Northern hemisphere, for the first half of 2023 Venus is quite well placed at over 30 degrees up towards the West for months in the evenings, fulfilling her role as the “Evening Star”. However from the start of May 2023 onwards, she’ll be getting lower in the sky, disappearing altogether by August. Thereafter, we won’t see Venus in the evenings until late 2024.

Southern Hemisphere

For Southern Hemisphere-ers, it's actually not so different, visible in the evening getting higher and higher until late June 2023. Thereafter again, we won’t see Venus in the evenings until late 2024.

In support, the charts of Venus’ altitude I present below are of Venus just after sunset, viewed from the Northern latitudes, London, and from Southern latitudes, e.g. Sydney or Capetown.



Mars (updated May 2023)

Mercury’s and Venus’ orbit sit inside Earth’s orbit, meaning from an Earthly observer's point of view, they each appear to “follow the Sun around”, either ahead or behind. Consequently Mercury offers few opportunities for observing, and Venus is known as the Evening Star or Morning Star, depending on which side of the Sun she is.

Mars is different. His orbit, the outermost of the 4 “rocky” planets, sits outside Earth’s orbit. This means that Mars’ distance from and apparent size from an Earthly observer varies enormously, from as little as 4 arc-seconds (1 arcsec=1/3600 of a degree), when Mars and Earth are at opposite sides of the Sun, to more than five times bigger at over 22 arc-seconds when they’re both at the same points on their orbits and closest together.

LEFT: Closest Together (Opposition) ............. RIGHT: Far Apart
 .......



Because Earth orbits inside Mars, we necessarily orbit faster (Kepler’s 3rd Law), in fact about twice as fast. So the two planets get back to approximately their same relative positions every two-ish years. Thus a chart of Mars’ altitude (to an Earth-bound observer) will show a roughly two-year periodic pattern. Put another way, if Mars is at its closest (and biggest - called "Opposition") say now, one year later it will be at its furthest away (and smallest), and vice versa.

Mars 2023-2024

Mars from mid latitudes either North or South Hemisphere will be similar during 2023-2024. He’s visible reasonably high up from early 2023 until the Summer wherever you are, but unfortunately heading away from us and well past his peak size. So a rather small target in a telescope, making detail rather difficult to see. Better from the Southern Hemisphere though, from an elevation point of view.

Northern Hemisphere



Southern Hemisphere



Jupiter (updated May 2023)

Hop over the Asteroid Belt from Mars, and we get to the first of our two Gas Giants and our largest and most massive planet, Jupiter. Jupiter is very bright, second only to Venus amongst the planets.

Jupiter orbits 5 times further from the Sun than earth, taking 12 years to complete an orbit. Along with Saturn, it’s truly the most spectacular planet to observe through a telescope, and is a real test of a scope’s quality. On a night of good “seeing” and with a scope of high quality, its bands and details within its bands are discernible, as well as the Great Red Spot. Its 4 largest Moons, the so-called “Galilean Moons”, Io, Europa, Ganymede and Callisto, can usually be seen as a line of bright dots near the planet even through decent hand-held binoculars.

Jupiter 2023-2024

Because Jupiter takes around 12 years to orbit the Sun, it will appear approximately 36 degrees further East at the same date each year. Its apparent altitude also changes each year, and at the time of writing (May 2023) Jupiter won’t re-appear for dark evenings until around November 2023.

In the Northern Hemisphere, Jupiter has been slowly improving “maximum altitude” year by year, at a rate of nearly 14 degrees higher per year. Next Jupiter season, Nov 2023 – Mar 2024, he will reach over 50 degrees up, the best for years! It’s going to be fantastic. In good conditions Jupiter's disc can reveal a wealth of detail, several bands, whorls, and barges within the bands, depending on the night’s seeing and the quality of your scope. A lot of Jupiter’s detail can be seen in colour, so ironically it's actually best observed in twilight, even quite bright twilight, when your Cones are still active (mesopic vision). Cones are your eyes’ colour cells, and they not only see colour, but are also more densely packed, so you see more detail too. By the time it’s truly dark, only your Rods are working, in monochrome (grey) and at less resolution (scotopic vision).

The Southern Hemisphere will be broadly similar, though peaking a couple of months earlier and reaching not quite as high as the NH at max elevation – a reversal of recent years.

Northern Hemisphere


Southern Hemisphere



Saturn (updated May 2023)

Next out from Jupiter orbits Saturn. Although Saturn’s orbit distance from the Sun is just under twice Jupiter’s, it takes almost 3 times as long to complete: nearly 30 years in fact (Kepler's Laws). Saturn is truly the Wow! or OMG! Planet, the reactions invariably elicited when people see Saturn through a telescope for the very first time. They never forget that first look, and most never lose the sense of wonder every time they see it. I certainly don’t.

Saturn has (as of May 2023) over 80 Moons of which several are visible in “backyard telescopes” such as ours. Its rings comprise almost entirely chunks of water ice, and the ring system is only about 20 metres (60 feet) thick! With a good telescope and good seeing, detail within Saturn’s rings can be seen, especially the so-called Cassini Division. Probably the same remarks about mesopic vision for Jupiter, see above, also apply to Saturn.

Saturn 2023-2024

The “observing pattern” of Saturn lately has been similar to Jupiter, as they have been quite close together in the sky, and they both move relatively slowly across the stellar backdrop. Indeed Saturn and Jupiter exhibited a “Great Conjunction” in December 2020, where they were nearly on top of one another! That was a sight to behold and won’t happen again until 2038. So good times for observing Saturn are not dissimilar to those for Jupiter, and indeed, like Jupiter, Saturn’s altitude for a NH observer is getting better year on year at the moment, just over 3.5 degrees higher at max per year, and improving for we NH-ers for at least a decade yet.

Through a telescope, many of Saturn’s Moons are visible, though dimmer than the Jupiter's "big four".

So for the NH, Autumn-Winter will be Saturn season, rising to 25 degrees by Christmas and disappearing in the evenings by mid January. For SH-ers, Saturn’s pattern is similar, but peaks higher and for a slightly shorter time over the same months, i.e. during the SH Spring.

Northern Hemisphere


Southern Hemisphere



Uranus (updated May 2023)

Uranus is the inner of the two “Ice Giants” (Jupiter and Saturn are the “Gas Giants”). Uranus is an oddity in some ways. The rest of the Solar System all mostly rotate and orbit in the same sense (Conservation of Angular Momentum of the gas cloud whence the Solar System was formed). If you were to look down from a long way above the solar system, you would see that all the planets orbit in more or less the same plane around the Sun, called The Ecliptic, they all orbit the Sun in the same direction and they nearly all rotate in that same direction. Which means their polar axes all point “up”, perpendicular-ish to the ecliptic and their orbits. Uranus is an exception. Uranus has been “tipped over”, so its rotational axis is on its side. Which makes for very odd sunrises and sunsets! (Venus is also an oddity – it orbits like the rest, but rotates about its axis the other way).

Uranus orbits nearly twenty times further from the Sun than Earth, and takes 84 years to complete an orbit. It starts to allow the heavens give human lifespan some perspective.

For observers, Uranus is just beyond naked eye for all but the very darkest skies and the sharpest eyes. Through a scope, however, it’s easily found, clearly blue-greenish and clearly a disc not a star.

Uranus 2023-2024

From NH skies, Uranus will only start to become observable again after November 2023, and will rapidly rise to 55 degrees elevation by early 2024. For SH observers, the pattern is similar, except peaking slightly earlier and lower.

Northern Hemisphere


Southern Hemisphere



Neptune (updated May 2023)

Neptune is the outer of the two “Ice Giants”, orbiting 30 times as far as the earth and taking 165 years to complete an orbit around the Sun. To observe through a telescope, it’s a bit more of a challenge than Uranus, though under the right conditions it does appear greenish and as a disc, but you need high magnification to discern the latter. An experienced observer will certainly be able to find it.

Neptune 2023-2024

From either hemisphere, Neptune becomes realistically visible from Sep 2024 until end-Jan 2024, reaching some 20 degrees higher in the SH than the NH.

Northern Hemisphere


Southern Hemisphere




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