What planets are visible tonight?
Five planets can be seen without a telescope: Mercury, Venus, Mars, Jupiter and Saturn. Which of them are visible tonight depends entirely on two things, the date and where you are standing, because a planet that is beautifully placed in Arizona can be below the horizon in Scotland at the same moment. That is what the row at the top of this page answers. It lists only the planets that actually clear ten degrees above your horizon in a dark sky tonight, and the hours each one spends up there.
Ten degrees is the line worth caring about. Lower than that and you are looking through five or six times as much atmosphere as you are at the zenith, which turns a planet into a smeared, wobbling blob. It is also the number that keeps the answer honest. Mercury will sometimes show a ten minute window and nothing more, and a page that told you Mercury was "visible tonight" without saying that would be wasting your evening.
How to read the two views
Your sky is the view you would get standing outside and turning to face the planets. The bottom edge is your horizon, the numbers up the side are degrees above it, and the letters along the bottom are compass directions. Hold your fist at arm's length: that is roughly ten degrees, so a planet at thirty degrees is three fists above the horizon. It is a star map for tonight rather than a chart of the whole sky, and only the brightest named stars are drawn, as landmarks, so the planets stay easy to pick out.
Solar plane is the same moment seen from above: a live solar system map with the Sun at the middle, the orbits drawn to scale in angle, and the little red dot on the Earth showing where you are on the globe at that hour. The thin lines running out from Earth are your lines of sight. When two of those lines nearly overlap, the two planets appear close together in your sky, which is all a conjunction ever is. Distances are squeezed so Mercury and Saturn fit on one screen, so do not read the gaps as real spacing. The angles, which are the part you actually see, are exact.
Conjunctions, oppositions and greatest elongation
These are the words that turn planet watching from luck into planning. Each one describes a piece of geometry you can watch happening in the solar plane view.
What is a conjunction in astronomy?
A conjunction is two objects appearing close together in the sky. They are not close in space at all. A Mars and Jupiter conjunction puts one of them about two light minutes away and the other about forty, but your two lines of sight happen to point almost the same way. The number that matters is the separation in degrees. Under about five degrees a planetary conjunction is striking. Under one degree, hold up your little finger at arm's length and it covers both. Those are the nights worth driving for. The events panel lists every one coming, so a Venus and Jupiter conjunction or a Moon and Venus conjunction shows up with its date and its real separation rather than a vague "later this month".
What does opposition mean in astronomy?
The Earth passes directly between the Sun and an outer planet, so that planet sits opposite the Sun in our sky. It rises as the Sun sets, it is highest around midnight, and it is closest to us, so it is at its biggest and brightest for the year. If you own a telescope and you only get a few good nights, spend them within a month either side of opposition. Mars swings the most: near opposition it can be six times brighter than at its worst.
Greatest elongation
Mercury and Venus orbit inside us, so from here they never wander far from the Sun. They swing out to one side, stop, and come back. Greatest elongation is the moment they are farthest out, and it is the best chance you get. Greatest eastern elongation means the evening sky, so look west after sunset. Greatest western elongation means the morning sky, so look east before dawn. That reversal catches everybody out once. Venus reaches about 46 degrees. Mercury only manages 18 to 28 depending on where it is in its stretched little orbit, which is exactly why so many people have never knowingly seen it.
Inferior and superior conjunction
The two ends of that swing. At inferior conjunction Venus or Mercury passes between us and the Sun and switches from the evening sky to the morning sky. At superior conjunction it goes behind the Sun and disappears for a few weeks. Superior planets have a solar conjunction too, and it is the six weeks of the year when they are simply not available.
Retrograde motion
Watch a planet against the stars for a few months and it drifts steadily east, then slows, stops, and backs up for a while before carrying on. Nothing has reversed. Retrograde motion is a parallax effect: Earth, on a faster inside track, overtakes the outer planet, and the line of sight swings backwards the way a car you pass on the motorway appears to slide rearwards against the hills. Switch to the solar plane view around an opposition and step forward a night at a time. You can watch your own sight line sweep back through the planet, which is the whole explanation in about ten seconds.
The synodic period, or why the same events keep coming back
Every pairing runs on a clock called the synodic period, the time it takes two planets to return to the same arrangement as seen from Earth. Venus repeats every 584 days, which is why its evening and morning apparitions arrive in a slow rhythm. Jupiter reaches opposition every 399 days, so it drifts about a month later each year. Nothing here is random, and once you notice the rhythm the calendar stops feeling like news and starts feeling like a timetable.
Planetary alignment and planet parades
Every so often a planetary alignment leads the news and the pictures show the planets in a tidy line stretching off into space. That is not what is happening, and the real thing is better. The planets all orbit in roughly the same flat plane, so from our seat inside it they are always strung along the same line across the sky. A planet parade is simply several of them being on our side of the Sun at once, high enough and far enough from its glare to be seen in one evening.
So the honest question is never "is there a planet alignment tonight", it is "how many of them can I see from here, and when". The row at the top of this page answers exactly that, and it will tell you when a headline is overselling: a parade that includes Uranus and Neptune is a parade you need a telescope and a finder chart to attend. Four or five naked-eye planets up together in a dark sky is genuinely rare and worth rearranging an evening for. Scrub the date rail forward and the count changes night by night, which is the quickest way to find the next one.
What is the ecliptic?
The dashed line curving across the sky view is the ecliptic, and it is the most useful thing on the screen. It is the Sun's apparent path through the year, and because the solar system is nearly flat, it is also the line the Moon and every planet ride along. The ecliptic plane is the plane of Earth's orbit; everything else sits within a few degrees of it, which is why the planets are never scattered randomly and why they always turn up among the same twelve or thirteen constellations.
Learn to find that line and you have a permanent skill. It runs high across the sky on winter evenings and low on summer ones, from a rising point south of east to a setting point south of west. Anything bright sitting on it that is not on your star chart is a planet.
The evening star and the morning star are the same planet
Both are Venus. When Venus is east of the Sun it sets after it and hangs in the west as the evening star. When it is west of the Sun it rises first and burns in the east before dawn as the morning star. It swaps between the two at inferior conjunction, and the whole cycle takes about nineteen months.
Venus is the brightest planet in the sky by a wide margin, bright enough to cast a shadow on a dark night and bright enough to be reported as a UFO several times a year. It also goes through phases like the Moon, which is what the portrait at the top of this page is showing you: a fat little disc when it is far away on the other side of the Sun, a thin dramatic crescent when it is close and about to pass us. The crescent is large enough that steady binoculars will show it, and seeing it for yourself is one of the genuinely great cheap thrills in astronomy.
Why don't planets twinkle?
Here is the field trick that costs nothing. Stars twinkle, planets mostly do not. A star is so far away that it is a true point of light, and every pocket of moving air in our atmosphere shoves that point around. A planet shows a tiny disc instead, a few tens of arcseconds across, and the shoving averages out across it.
So that is how to tell a planet from a star: a bright, steady, unblinking light sitting near the ecliptic is almost certainly a planet. Colour helps too. Mars is properly orange, Jupiter is cream white, Saturn is a softer yellow. Near the horizon even planets will flicker, because you are looking through far more air, so judge it when the object is reasonably high.
What is that bright star next to the moon?
Almost always a planet. The Moon travels along the ecliptic too, so it passes the planets constantly, and a close Moon and planet pairing is the single most noticed thing in the night sky. If it is brilliant and white it is Venus or Jupiter. If it is orange and steady it is Mars. If it is modest and yellowish it is Saturn.
A bright light in the sky that is moving is something else: a satellite crossing in a straight line for a few minutes, an aircraft if it blinks, or a Starlink train if it is a line of them. Set the date and time here and check the sky view. If nothing is drawn where you are looking, it is not a planet.
Can you see Mercury with the naked eye?
Yes, and most people never have. Mercury is not faint, it often outshines every star in that part of the sky. The problem is that it never gets far from the Sun, so it only ever appears low, in twilight, for a couple of weeks at a time, and you have to already know where to look.
The recipe: pick a date within a few days of greatest elongation from the events list, get a horizon with nothing on it in the right direction, and start looking about half an hour after sunset or before sunrise. The row at the top gives you the window in real numbers, and if that window is ten minutes long, that is the truth about your particular Mercury apparition rather than a reason to doubt yourself.
Does the moon change any of this?
For the planets themselves, hardly at all. Venus and Jupiter cut straight through moonlight and through city light, and plenty of people have seen a beautiful conjunction from a parking lot. But the moment you want anything else in the frame, the Milky Way behind the planets, the faint ones, the sense that the sky has depth, the moon becomes everything. That is why the timeline washes pale whenever the moon is above the horizon: a bright moon does not hide the planets, it erases everything around them.
Find the dark skies near you
Once you have used this for a while you start to notice that the good nights are the ones where the planets are up, the moon is down, and you are somewhere the rest of the sky can keep up with them. The first two you can read straight off this page. The third one is a place, and it is usually closer than people assume.
Learn how to find dark skies near you
How this tool works
Positions come from the JPL approximate orbital elements for Mercury through Saturn and a truncated lunar series, computed in your browser with no data sent anywhere. Coordinates are precessed to the date, corrected for light travel time, and the Moon is corrected for your position on the Earth's surface, which moves it by up to a degree. Everything was checked against pyephem: planet positions agree within 0.01 degrees for Mercury through Mars and 0.08 degrees for Jupiter and Saturn, rise and set times within thirty seconds, magnitudes within 0.2, and phases within 0.1 percent. Rise and set use the standard refraction convention, so times are for a flat, open horizon. A ridge to your east delays a rise, sometimes by a lot.