Is that bright light a planet?
This is a short guide to checking a light you saw in the sky. Four quick observations narrow it down. Then you can set the place and time you saw it on the sky map and see which planet, star or Moon stood there.
It works for tonight and for last night: set the time you saw the light, not the time it is now.
Live sky
Calculating the sky for your local date and place…
The sky view appears here when its calculation loads.
Local time in the selected city.
Quick identification
Is it moving across the sky within a minute?
- Blinking red, green or white lights — an aircraft.
- A steady point gliding silently, then fading out — likely a satellite, such as the International Space Station.
- A line of evenly spaced points moving together — likely a Starlink “train”, seen in the days after a launch.
- A streak lasting a second or two — a meteor.
- Any of these — Above Tonight draws only the Sun, the Moon, the planets and stars, so it does not draw aircraft, satellites, Starlink trains or meteors. Nothing on the map at that spot is itself a clue.
Not moving: does it twinkle strongly, high in the sky?
- Twinkles and flashes with color, high up — likely a star, such as Sirius, Arcturus, Vega or Capella.
- Steady, even though it is high up — likely a planet.
- Low near the horizon — this clue fails. Even a planet can flicker low down, so go on to the next question.
Steady and very bright near dusk or dawn, low in the west or east?
- Brilliant white, low in the west after sunset or in the east before sunrise — likely Venus.
- Fainter, very low in twilight — possibly Mercury, which is seen for only a few weeks at a time.
- Bright and steady, and still high at midnight — possibly Jupiter, which can stand anywhere along the Sun’s path. Venus never does.
- Reddish-orange — possibly Mars. Pale yellow and modest — possibly Saturn.
Then check the map
- Set the place and time you saw it — not the time it is now. Turn to the direction and height you noted.
- A planet or star is drawn there — it is a candidate for what you saw, not proof.
- Nothing bright is drawn there — the light may be something the map does not draw, such as an aircraft or a satellite.
The one-minute method
- Is it moving? Watch it for a minute. A planet or a star stays put among its neighbors; over hours the whole sky turns, but not over one minute. A light that travels steadily across the sky is not a planet or a star. Above Tonight does not draw or identify what it is, such as an aircraft or a satellite.
- Is it steady or twinkling? Stars are points of light, so moving air makes them twinkle. A planet is a tiny disc and usually shines steadily. Low down this clue fails. Near the horizon the light crosses much more air, and even a planet can twinkle and flicker in color. A steady light high up counts for more than a twinkling light low down.
- Which direction, and when? Note the compass direction and the time, and whether it was after sunset or before sunrise. Mercury and Venus never stray far from the Sun, so they appear low in the west after sunset or low in the east before sunrise. Mars, Jupiter and Saturn follow the band of sky that the Sun and Moon follow. From the northern hemisphere that band lies mostly in the southern half of the sky, and from the southern hemisphere in the northern half.
- How high? A fist held at arm's length covers about 10 degrees of the sky (the Planetary Society gives the same rule). The horizon is 0 degrees and straight up is 90. Two fists up is about 20 degrees.
Write the four answers down with your place, the date and the time. Then compare them with the sky map.
Open the sky map and set the place and time you saw the light
Four examples
- Venus. The brightest planet, steady and white. It stays close to the Sun, so you find it low in the west after sunset or low in the east before sunrise, and never high in the sky at midnight.
- Jupiter. Usually brighter than any star, and steady. It can stand anywhere along the Sun's path, high up at midnight at some times of the year.
- Sirius. The brightest star in the night sky. It twinkles strongly, and near the horizon it flashes red and blue.
- A light that moves steadily across the sky. It is not a planet or a star. Above Tonight does not tell you what it is.
Checking your own sighting
Say you notice a steady, bright light low in the east-southeast about an hour after sunset. It does not twinkle and does not move. This is how you would check it, for your own place and time.
- Write down what you saw. The place you stood, the date and time, the direction (east-southeast), the height (about two fists, so about 20 degrees), and whether it was steady, twinkling or moving.
- Open the sky map and set the place and time you saw it. Use the time of the sighting, not the time it is now.
- Look in that direction and at that height. Turn the view to east-southeast and about two fists above the horizon. See which planet, star or the Moon is drawn there. Select it, and the details give its direction and height and say whether it is above or below the horizon.
- Compare it with what you saw. Is the object within about 5 to 10 degrees of where you looked? Does it fit the clues: a planet shines steadily, a bright star may twinkle? If nothing bright is drawn there, the light may be something Above Tonight does not draw, such as an aircraft or a satellite.
A match means a planet, star or the Moon stood in that direction and at that height at that moment, and it is a candidate for what you saw. It does not prove it: a light that twinkled hard or moved would point somewhere else.
What this cannot tell you
A match in direction and height is a candidate, not proof. Color and steadiness are clues that can mislead, and estimating a direction or a height by eye is rarely better than about 5 to 10 degrees.
- Above Tonight does not identify aircraft, satellites or any unknown object, from a description or from a photograph. It does not draw comets, asteroids or meteors.
- It draws the Sun, the Moon, the seven planets, 743 stars and 88 constellation figures. A star outside that catalogue is not drawn.
- It does not model weather, haze, light pollution, terrain or buildings. A planet above the horizon is not a promise that you could see it.
- Positions are geometric and ignore atmospheric refraction, which lifts objects near the horizon by up to about half a degree.
Questions people ask
What is the strange bright light in the sky tonight?
Most often a planet, usually Venus or Jupiter, or a bright star. If it moves or blinks, it is an aircraft or a satellite. Note the direction, the height and whether it twinkles, then set that place and time on the sky map to see which planet or star stood there.
What is that moving white light in the sky?
A steady light gliding silently across the sky is usually a satellite, and one that blinks is an aircraft. A line of evenly spaced lights can be Starlink satellites after a launch. Above Tonight does not draw aircraft or satellites, so the map will not show them.
How can I tell if it’s a planet or a star?
Stars twinkle because moving air disturbs their point of light; planets are tiny discs and usually shine steadily. The clue fails low down. A dependable check is position: planets stay close to the band of sky the Sun follows, and the sky map shows which planets stand where.
Which planet is mistaken for a star?
Venus and Jupiter most often, because they are brighter than any star. Venus appears low in the west after sunset or in the east before sunrise, and the evening or morning “star” is usually Venus. Mars is sometimes taken for a red star, and Saturn for an ordinary pale one.
How rare is seeing Starlink?
A Starlink train is a short-lived sight: it is most visible for a few days after a launch, shortly after sunset or before sunrise, while the satellites are still in a line. Later they spread out and fade. Above Tonight does not draw satellites, so use a satellite-pass predictor for times.