To help people understand the astronomical phenomena, Chunghwa Post is offering a set of four stamps and a souvenir sheet. The stamps are described below:1. Annular Solar Eclipse (NT$6): When the Sun, Moon and Earth are in near-perfect alignment and the Moon is relatively far from the Earth, people in the antumbra of the Moon see the Sun only as a halo of light like a golden ring. This is an annular solar eclipse. 2. Comet (NT$6): Comets are small bodies in the solar system, popularly called “broom stars.” Those following an elliptical orbit will return after passing around the Sun and are called periodic comets, exemplified by the well-known Comet Halley, which returns about every 76 years. 3. Total Solar Eclipse (NT$8): When the Sun, Moon and Earth are in near-perfect alignment, people within the umbra of the Moon see the phenomenon that the Moon totally blocks the sunlight and this is a total solar eclipse. Such an eclipse usually only lasts a few minutes. The sky turns dark as if night had fallen. 4. Total Lunar Eclipse (NT$8): When the Sun, Earth and Moon are in near-perfect alignment and the Moon falls completely into the umbra of the Earth, there is a total lunar eclipse. At such times only the longer wavelength red light of the Sun shines on the Moon by refraction through the Earth’s atmosphere producing a deep red look.