Stamp: Planetary system (Tonga 1986)
Planetary system (Tonga 1986)
26 March (Tonga ) within release Halley's Comet goes into circulation Stamp Planetary system face value 57 Tongan shilling
| Stamp Planetary system in catalogues | |
|---|---|
| Michel: | Mi:TO 939 |
Stamp is square format.
A planetary system is a set of gravitationally bound non-stellar objects in orbit around a star or star system.Also in the issue Halley's Comet:
- Stamp - Halley's Comet face value 42;
- Stamp - Edmond Halley face value 42;
- Stamp - Planetary system face value 42;
- Stamp - Telescope face value 42;
- Stamp - Giotto, European Space Probe face value 42;
- Stamp - Halley's Comet face value 57;
- Stamp - Edmond Halley face value 57;
- Stamp - Planetary system face value 57;
- Stamp - Telescope face value 57;
- Stamp - Giotto, European Space Probe face value 57;
- Se-tenant - Halley's Comet face value 5*42;
- Se-tenant - Halley's Comet face value 5*57;
Stamp Planetary system it reflects the thematic directions:
A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or coma surrounding the nucleus, and sometimes a tail of gas and dust gas blown out from the coma. These phenomena are due to the effects of solar radiation and the outstreaming solar wind plasma acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch beyond one astronomical unit. If sufficiently close and bright, a comet may be seen from Earth without the aid of a telescope and can subtend an arc of up to 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures and religions.
