The Ghostly Glow of Gegenschein

By: Alan Dyer

Mar 19 2017

Tags: , , , , , , , , ,

Category: Constellations, Nightscape, Solar System, World at Night

3 Comments

Aperture:f/2.5
Focal Length:14mm
ISO:3200
Shutter:25 sec
Camera:Canon EOS 6D

It takes a dark spring night to see it well, but now lurking near Jupiter is a ghostly sky glow called Gegenschein. 

This diffuse glow lies directly opposite the Sun. It is caused by sunlight reflecting off interplanetary dust particles in the outer solar system. They reflect light more effectively at the anti-Sun point where each dust particle is fully lit by the Sun.

Like the Sun, the Gegenschein moves around the sky along the ecliptic, moving about a degree from west to east from night to night. March and April provide good nights for seeing the Gegenschein as it then lies in an area of sky far from the Milky Way.

Even so, it is very subtle to the unaided eye. Look south at about 1 a.m. local daylight time.

However, this year, in early April the Gegenschein will be more difficult as it will then lie right on top of Jupiter, as that planet reaches its point opposite the Sun on April 7. Jupiter will then be superimposed on the Gegenschein.

The main image at top is a 7-image vertical panorama of the spring sky, from Corvus and Virgo above the horizon, up past Leo, into Ursa Major and the Big Dipper overhead. Spica lies below bright Jupiter, Arcturus in Böotes is at left, while Regulus in Leo is at right. The grouping of stars near centre is the Coma Berenices star cluster.

Orion over the Old Barn

Earlier in the night, I shot the sky’s other main glow – the Milky Way, as the winter portion of the Milky Way around Orion set into the southwest.

But over in the west, at the right edge of the frame, is the Zodiacal Light, caused by the same dust particles that create the Gegenschein, but that are located in the inner solar system between us and the Sun.

The Zodiacal Light is better depicted in images in my previous post from Dinosaur Park

We bid adieu to the winter Milky Way now. As it departs we are left with an evening sky without the Milky Way visible at all. As seen from northern latitudes it lies along the horizon.

But later in spring, late at night, we’ll see the summer Milky Way rising, beginning its seasons of prominence until late autumn.

— Alan, March 19, 2017 / © 2017 Alan Dyer / AmazingSky.com 

 

3 comments on “The Ghostly Glow of Gegenschein”

  1. Last month at the Winter Star Party in the Florida Keys, around local midnight, I was lying back enjoying Leo high overhead. Earlier, we had seen Venus and Mars embedded in the Zodiacal Light. I convinced myself that I saw a wide glow to the east and south of Regulus. Checking with SkySafari, it turned out to be exactly where the GS should have been. I took a photo, but it is unconvincing. I may need to remove the vignetting if the wide-angle lens somehow.

    • It doesn’t take a long tracked exposure but a very fast lens – I shot at f/2 – helps. But then removing the vignetting in Camera Raw using lens correction. There are or sets for manual Rokinon lenses but you have to pick them manually. It won’t auto detect them.

  2. Wow!!! Excellent night sky detective work. I always learn something on your blog.

    On Sun, Mar 19, 2017 at 10:54 AM The Amazing Sky wrote:

    > Alan Dyer posted: ” It takes a dark spring night to see it well, but now > lurking near Jupiter is a ghostly sky glow called Gegenschein. This > diffuse glow lies directly opposite the Sun. It is caused by sunlight > reflecting off interplanetary dust particles in the outer so” >


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