Astronomy Essentials

What are star trails, and how do I photograph them?

Above the silhouetted mountains, star trails glow in bright, colorful arcs circled around a central point in the sky.
View at EarthSky Community Photos. | Amrinderjit Singh captured these star trails from Pangong Lake, nestled 4,350 meters above sea level in the Himalayas on May 16, 2023. Amrinderjit wrote, “Behold the mesmerizing dance of stars. As the night falls, it transforms into a celestial canvas, painted with streaks of yellow, blue, and pink, courtesy of the star trails swirling above. Each streak represents the movement of Earth beneath the starlit sky, a silent yet profound reminder of our place in the cosmos. Capturing this moment was a blend of patience and wonder as I marveled at nature’s masterpiece unfolding before my eyes.” Thanks, Amrinderjit!

What are star trails?

Star trails show the motion of the stars over the sky during a period of minutes or hours. With a steady mount, long exposures and a few other tricks, you can take images of star trails, too. Often, the camera stays pointed at Polaris, the North Pole Star. In the Southern Hemisphere, photographs can point at the south celestial pole (not marked by a single star). Then, with an open shutter, the camera records an image as Earth turns on its axis and the stars move overhead. There are also many variations on star trail photos, as you’ll see here!

Star trails reflect Earth’s rotation, or spin, around its axis. The Earth makes a complete rotation relative to the backdrop stars in a period of about 23 hours and 56 minutes. So, as seen from Earth, all the stars go full circle and return to the same place in the sky after this period of time. This revolution with respect to the stars is what astronomers call a sidereal day.

Earth’s spin makes star trails

What this means is that, if you’re standing out under the stars, you see them move across the sky as the night progresses. The stars – like the sun during the daytime – move from east to west across the sky every night.

Stars near the celestial poles produce the smallest circles, while those near the celestial equator produce the largest. Each and every star moves 15 degrees westward in one hour.

Star trails are really arcs, or partial circles, whose ever-circling motions forever tabulate the passage of time.

What are star trails? Dashes of light in a circle with black metal object in foreground.
View at EarthSky Community Photos. | Cameron Frankish in Longdown, Devon, U.K., captured this photo of star trails on April 6, 2021. He wrote: “Originally planned to do a total of 1,000 shots, but the cloud came in after 240.” Thank you, Cameron!

What you need to capture star trails

EarthSky Facebook friend Ken Christison has some wonderful photos of star trails. He said the equipment needed for making star trails is pretty simple:

First, a camera that allows manual settings so you can set your f/stop and shutter speeds, as well as ISO.

Next, a wide angle lens, the wider the better.

A good steady tripod is a must.

Some cameras will have a built-in intervalometer, which can be set to shoot the desirable number of frames. In some cases the intervalometer has a bit of lag between shots. This is the reason I use a separate remote attached to the camera that holds the shutter down. And when the camera is set in continuous shooting mode, it will shoot 100 frames in succession with very little gap.

The remote I use is a simple one that can be found on eBay and uses a couple of AAA batteries that last quite a while. I just use the remote controller attached to the 10 pin connector. There is no need to use the wireless receiver in this case.

I use a shutter speed of 30 seconds, ISO of 400 to 800, and – with my 14-24mm lens at 14mm – shoot it wide open at f/2.8.

Star trails above with rocky landscape below and Half Dome in the distance.
View at EarthSky Community Photos. | Ron Andersen in Yosemite National Park, California, captured these star trails on July 4, 2023. Ron wrote: “160 photos taken under the July full moon over Yosemite Valley.” Thank you, Ron!

How to photograph the timelapse streaks

Next, Ken said, you’re ready to capture your star trail:

Make sure the camera is level. After focusing on a star, make sure the autofocus is turned off. Then, using the settings mentioned above, click the shutter and stay around long enough to know that the shutter is actually actuating. I normally go back in the house, set the timer on our kitchen stove for 45 minutes, and do other things while the camera does its work.

When the timer sounds, go back out and reset the remote by turning it off, waiting for the shutter to close, then reset quickly.

Finally, you’ll want to process your photo. Ken said:

This is one of the most important elements in making star trail images. The program I use is free, works well and is simple to use: Startrails.exe.

One other program that I have heard works well and is also free is StarStaX.

Thank you, Ken!

Visit Ken Christison’s Facebook page.

Read more: Long exposure star trail photography

Star trails from our community

Light blue sky with short, concentric white lines and a white streak, with body of water below.
View at EarthSky Community Photos. | David Cox in Deep River, Ontario, Canada, captured this photo of star trails and a Draconid meteor on October 8, 2021. He wrote: “Polaris timelapse captured a single, impressive Draconid meteor streak over the Ottawa River.” Thank you, David!
Foreground buildings with streaks of stars and one dotted plane trail in sky.
View at EarthSky Community Photos. | Soumya Seal in Kolkata, India, captured these star trails on July 7, 2023. Unlike higher latitudes, star trails closer to the equator draw less of a circle. Soumya wrote: “Nearer the celestial equator we get long star trails across the sky.” Thank you, Soumya!
Short streaks of light in concentric circles against a black background.
View larger at EarthSky Community Photos. | Cameron Frankish captured this image in Dartmoor, Devon, U.K., on October 21, 2019. He wrote: “Polaris star trail with an Orionid meteor (possibly) in the bottom left.” Thanks, Cameron!
Round star trails with dotted streaks of airplanes plus a city below and starlink trails in corner.
View at EarthSky Community Photos. | Meiying Lee in Taoyuan, Taiwan, captured these star trails on May 27, 2023. Meiying wrote: “I captured and stacked this photo of star trails near Taiwan’s largest international airport. The red dashed line represents the trail of a distant ship, which happened to mark the position of the sea level. What surprised me the most were the numerous short and momentary trails in the lower-left part of the photo. Upon closer examination, I noticed that these trails were concentrated near the western part of the northern horizon, suggesting they were Starlink satellites.” Thank you, Meiying!

Moon and sun trails from our community

Overhead view between trees of the moon in multiple spots in a line.
View at EarthSky Community Photos. | Matthew Chin in Hong Kong took these images over a week in March 2023, creating a moon trail. Matthew wrote: “If you have an open view, you can take moon photos at the same time and same location from around lunar day 6 to 21.” Thank you, Matthew! Another way to capture a moon trail is to make multiple exposures of the moon over the same night and track it as it sets (see below).
A row of crescent moons from upper left to lower right in sky.
View at EarthSky Community Photos. | Meiying Lee in Hsinchu, Taiwan, captured this moon trail on October 28, 2022. Meiying wrote: “I photographed the track of the moon setting for nearly an hour. Because of the enhanced exposure, earthshine appears clearly. Many of the red dots below are wind turbines on the shore or on the sea.” Thank you, Meiying!
Sunset sky with multiple sun images moving toward horizon and small point of Mercury beside it.
View at EarthSky Community Photos. | Meiying Lee in Taipei, Taiwan, shared this sun trail with Venus and Mercury from December 24, 2022. Can you find all the solar system objects as they set? The sun, Mercury, Venus and moon are all captured in this composite. Thank you, Meiying!
City with towering skyscraper and two lines marking Venus and Jupiter trailing down behind the tower.
View at EarthSky Community Photos. | Meiying Lee in Taipei, Taiwan, captured trails of Venus and Jupiter on March 2, 2023. Meiying wrote: “Venus and Jupiter set side by side in the night sky of Taipei.” Thank you, Meiying!

A star trails video

Night shot showing stars and the lines they leave as they move.
EarthSky’s own Raúl Cortés captured this video of star trails on July 13, 2023, from Monterrey, Mexico. The bright orange streak near the horizon is the star Antares in the constellation Scorpius the Scorpion.

Bottom line: Star trails are photographs of the sky taken with long exposures. The result is an image with stars trailing across the sky in concentric streaks, often whirling around one of the celestial poles. But you can also take photos of sun trails, moon trails, or trails of the planets.

July 15, 2023
Astronomy Essentials

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