Астронет: Астрономическая картинка дня Окружая Солнце http://variable-stars.ru/db/msg/1917326/eng |
Credit & Copyright: Radoslav
Zboran
Explanation:
Earth's
orbit around the Sun
is not a circle, it's an ellipse.
The point along its elliptical orbit where our fair planet is
closest
to the Sun
is called perihelion.
This year, perihelion was on January 2 at 01:00 UTC, with
the Earth about 3 million miles
closer to the Sun than it was at aphelion (last July 6),
the farthest point in its elliptical orbit.
Of course, distance from the Sun
doesn't
determine the seasons,
and it doesn't the determine size of Sun halos.
Easier to see
with the Sun hidden behind a tall tree trunk,
this beautiful ice halo forms a 22 degree-wide
circle around the Sun,
recorded while strolling through the countryside
near Heroldstatt, Germany.
The Sun halo's 22 degree angular diameter is
determined by the six-sided
geometry
of water ice crystals
drifting high in planet Earth's atmosphere.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.