Astrophotography by Anthony Ayiomamitis

Solar Image Gallery - Scenic Phenomenon

A common misconception is that the sun is larger when it is near the horizon than when it is high overhead. However, this optical illusion is not true, for the apparent size of the sun is virtually the same when it is rising or setting near the horizon or when viewed overhead (in fact, it is very slightly smaller when viewed near the horizon due to refraction as well as the greater added distance in observing across the earth's radius). This illusion has been wrongly attributed to landmarks near the horizon, such as homes and trees, supposedly giving a sense of perspective and whereas the same perspective is lost when looking at the overhead sun bathed in an empty sky. As noted by Donald E. Simanek and Carl J. Wenning, the real reason behind this trick by our brain is the perception of the sun (or moon) being against a "close" or "distant" foreground and which is lucidly described by the above two references.

However, if we were approach the apparent size of the sun methodically by studying it during perihelion and aphelion, we can detect a small change using photographic equipment thanks to the elliptical orbit of our planet around the sun which leads to variations in distance (and apparent size) of the order of about 3.4%. More specifically, at perihelion each January, earth is approximately 147 million km away from the sun and whose apparent diameter is about 32.53' whereas, at aphelion each July, earth is approximately 152 million km away and the sun is characterized with an apparent diameter of about 31.46'. This difference of 5 million km between perihelion and aphelion leads to the slight change in the apparent diameter of the sun as illustrated by the two images of the sun below captured six months apart when the sun was near its minimum possible perihelion (Jan 2/2005) and maximum possible aphelion (Jul 5/2005) and while crossing the local meridian.

Note: The change in the apparent diameter of the moon is MUCH more dramatic between perigee and apogee and is fully documented elsewhere on this website (see here).


Image Details
Sun at Aphelion and Perihelion
Imaging Details
Body:
Sun

Mass:
332,900 x Earth

Mean Eq Diameter:
109.1 x Earth

R.A / Dec:
18h 21m 42s /
-23 20' 57"


Distance:
Aph 152,102,363 km
Peri147,099,182 km

Diameter:
Aphelion 31.46 '
Perihelion32.53 '

Magnitude:
-26.8
Date:
Jan   02, 2005 (12:53:52 UT+2)
Jul   05, 2005 (13:09:24 UT+3)

Location:
Athens, Greece

Equipment:
TeleVue Pronto
TeleVue Zero-Length Adapter
Losmandy G-11 GEM
Canon EOS 300d
Baadar Solar Filter ND5


Exposures:
1/800, 1/2500 sec
ISO 100
RAW Image Format
3072x2048 Image Size
Manual Mode


Software:
Canon FileViewer V1.3.2
Photoshop V6


Processing:
RAW to TIFF (16-bit) Conv
Resampling (80%)
Unsharp Masking
Levels & Curves
Layers & Masks
JPG Compression