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A Saturn-like Star

20 April 2008

A Planet-mimicking Star
The picture shows a fascinating sunset over Alexandria, Egypt. Due to optical atmospheric effects, the Sun disc is reddened and flattened. The solar limb is also not smooth. The presence of thin clouds across the horizon rendered the Sun a banded appearance. Actually, the Sun resembles Saturn, the most flattened planet, when its magnificent rings lie in the plane of Earth’s orbit and become visible edge-on.
Photo by Aymen Ibrahem, Senior Astronomy Specialist

On the late evening of 2 April 2008, there were thin clouds across the western horizon in Alexandria, Egypt. The haze rendered the western sky and the setting Sun fascinating colors. BA Senior Astronomy Specialist Aymen Ibrahem imaged this amazing Sunset.

“Interestingly, the setting Sun was reddened and flattened due to optical atmospheric effects,” said Ibrahem. “The Sun disc shone like a banded red ellipsoid. The remarkable optical flattening of the Sun disc was reminiscent of Saturn, the most flattened planet. Also, Saturn shows cloud bands. The Sun rather resembled a red, ring-less Saturn.”

While the Sun is nearly a perfect sphere, the flattening of Saturn is due to its rapid axial rotation and mostly-fluid composition. Saturn’s equatorial diameter (approximately 120,000 km) and the polar diameter (approximately 109,000 km) differ by approximately 10%. Saturn is also the least dense planet, with a density of about 0.7 that of water.

Twice in its orbit, the rings of Saturn coincide with the orbital plane of Earth, and therefore, the extremely thin rings actually disappear for a short interval. The rings are then viewed “edge-on”. Only large telescopes can reveal the rings during the edge-on aspect of Saturn’s rings.

Ibrahem named his series of images “A Saturn-like Star”. The intriguing images show wonderful optical atmospheric phenomena, including the flattening and the distortion of the Sun disc near the horizon and the Sunset mirage. Some of Ibrahem’s images are presented in the picture gallery below.

Picture Gallery

Fig (1)
A Colorful Star
Due to refraction of sunlight through the relatively thick air layers near the horizon, the Sun disc shows gradients of yellow and orange.
Photo by Aymen Ibrahem, Senior Astronomy Specialist

Fig (2)
Photo by Aymen Ibrahem, Senior Astronomy Specialist

Fig (3)
A Banded Star
Photo by Aymen Ibrahem, Senior Astronomy Specialist

Fig (4)
A Balloon in Space
Photo by Aymen Ibrahem, Senior Astronomy Specialist

Fig (5)
A Bizarre Star
The photo shows the sunset mirage. The upper limb of a feeble Sun rises from the sea, merging with the setting Sun.
Photo by Aymen Ibrahem, Senior Astronomy Specialist

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