On March 29, Planet Saturn and the Moon stood perfectly in line and seemed to be touching each other in the night sky.
This relatively common but easily overlooked event is called conjunction. Fortunately, astrophotographer Grant Petersen was able to connect to a telescope-mounted smartphone.
Petersen took the stunning picture from Johannesburg, South Africa, and then shared it on Twitter for the whole world.
The picture is actually a combination of several photos showing Saturn just before the sunrise behind the moon.
Like many astrophotographers, Petersen constantly looks for "the next great astronomical event" to be visible at his site. Sometimes the event is a passing comet or asteroid, at other times it is the International Space Station which zips over.
Read More : NASA photographed the International Space Station in front of a total solar eclipse.
To find out what's coming, Petersen uses a variety of astronomical apps and diaries. In January, he noticed the Saturn-Moon conjunction, and he devised a plan to photograph it.
Petersen told Business Insider he had "great anticipation and excitement for the event", d. H. Until the rain arrived in Johannesburg the evening before. But the bad weather cleared and showed a clear night sky in time for the conjunction.
"When such an event occurs and everything goes according to plan and [we] can avoid problems like weather, equipment failure or human error, it feels like a great achievement," he said.
Petersen got up at four in the morning, or about two hours before the conjunction, to arrange and test his equipment. His setup included an 8-inch Dobsonian (a relatively cheap, but large and powerful telescope), a Galaxy S8 smartphone, an adapter for connection to a lens and an eyepiece.
When Saturn approached the moon, Petersen recorded it in a video at 60 frames per second. After the conjunction, he processed the images using a technique called stacking, which combines several lower-quality images into a brighter, clearer image. Then he shared his best photos with Twitter.
"At Christmas I felt like a kid," Petersen said. "I got a comment saying that they were reminded of the first Earthrise image of the Apollo missions."
Petersen also made the photo below, showing how small Saturn looks when it is 950 million miles from Earth. The planet seems to be only a tiny fraction of the diameter of the moon, which itself is small: about the width of the tip of your index finger, if you keep it at arm's length against the night sky.
Petersen said the next big event to photograph hopes is the passage of Mercury through the sun on November 11th.
"I'm really looking forward to it," he said.