Stand in the same spot every day. Take a picture of the Sun. What happens? Slowly, you see our closest star shifting positions in the sky. That motion over an entire year is called an analemma. The Opportunity rover on Mars even captured one on the Red Planet, which you can see above, and it’s a different shape than what you’ll find on Earth.
An April Astronomy Picture of the Day post (highlighted this weekend on Reddit) explains that Earth’s analemma of the Sun is figure-8-shaped, while that on Mars looks somewhat like a pear (or a teardrop, we think.) The Earth and Mars each have about the same tilt in their orbit — that same tilt that produces the seasons — but the orbit of Mars is more elliptical (oval) than that of Earth.
“When Mars is farther from the Sun, the Sun progresses slowly in the martian sky creating the pointy top of the curve,” the APOD post stated. “When close to the Sun and moving quickly, the apparent solar motion is stretched into the rounded bottom. For several sols some of the frames are missing due to rover operations and dust storms.”
The picture you see at the top of the post was taken every third sol (or Martian day, which is 24 hours and 37 minutes) between July 2006 and June 2008. The landscape surrounding the analemma is from Victoria Crater, where Opportunity was roaming at that time. (The rover is now on the rim of Endeavour Crater, still trucking after nearly 11 full years on the surface.)
In 2006, APOD also published a simulated analemma from Sagan Memorial Station, the landing site of the Sojourner spacecraft and tiny Pathfinder rover. In this case, the simulation showed the Sun’s movements every 30 sols. A Martian year is 668 sols.
You can read more details about analemmae in this past Universe Today post by David Dickinson, which relates the phenomenon to the passage of time.
Over the last few years I have been renovating my home. Building on Earth seems…
Astrobiologists continue to work towards determining which biosignatures might be best to look for when…
Planetary nebula are some of nature's most stunning visual displays. The name is confusing since…
The venerable Hubble Space Telescope is like a gift that keeps on giving. Not only…
The venerable Voyager 1 spacecraft is finally phoning home again. This is much to the…
The search for extrasolar planets is currently undergoing a seismic shift. With the deployment of…