Hello, tonight this stunning issue from Hong Kong Post. I
really like these. Hope you do. click
image to enlarge for better view.
The issue is titled
"Astronomical Phenomena".
Issued March 17th and showing seven
astronomical phenomena to introduce us to the fascinating world of astronomy.
$1.70 Solar Eclipse
When the Moon moves between the Sun and Earth and blocks the Sun, a solar
eclipse occurs. There are three types of solar eclipses: total solar eclipse,
partial solar eclipse and annular solar eclipse. When a total solar eclipse
occurs, in which the Sun is completely blocked by the Moon, the surrounding
environment on the ground suddenly turns dark. This dramatic change is
spectacular.
$2.20 Meteor Shower
When the Earth passes through the orbit of a comet, its meteoroids will enter
the Earth's atmosphere. Heated by the atmosphere, the meteoroids will become
visible as meteors. A meteor shower is an event in which an unusually large
number of meteors can be seen streaming from a certain point in the sky known
as the "radiant". Meteors from most meteor showers are fragments left
over by comets in space.
$2.90 Comet
A comet is a celestial body that travels between the outer and the inner parts
of the solar system. When it approaches the Sun, the temperature increases and,
affected additionally by solar radiation and charged particles, the dust and
rocks of the comet will be carried away or ionised, and separated from the
comet's surface. A comet normally shows two tails, one composed of dust and the
other of ionised gas.
$3.10 Saturn's Ring Tilt Variation
The tilting angle of Saturn's ring does not change with respect to Saturn
itself. However, if observed from the Earth, we will see that the tilting angle
of Saturn's ring appears to change. It is because the orbital period of the
Earth is one year, while that of Saturn is about 30 years. When the Earth
revolves once around the Sun, the relative position of Saturn also changes a
little bit.
$3.70 Sunspot
Sunspots are small black spots on the surface of the Sun which are related to
the magnetic activity of the Sun. A large group of sunspots may appear during a
peak in solar activity. Sunspots are in fact not dark. They only appear dark as
their brightness is lower than the normal surface of the Sun. Sunspots mostly
concentrate around the solar equator and can last for hours or months.
$5 Moon-Planet Conjunction
The orbit of the Moon and the orbit of the Earth and other planets lie nearly
in the same plane. So when we observe from the Earth, the Moon is sometimes
seen to be very close to other planets. We call it a conjunction when the Moon
and a planet are at an apparent closest approach. A Moon-planet conjunction may
form an interesting pattern such as the "smiley face" in the stamp.
Interesting, I hope you agree. Enjoy your stamps. Thanks to Hong Kong Post for the information. Well done.
Michael
