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Astro-Trivia:  1 | 2 | 3 | 4


The point in the Moon's orbit closest to the Earth.


The point in the orbit of a planet, asteroid, or comet at which it is closest to the sun.

size matters

If our Sun were much larger or smaller than it is, life on Earth could not exist. Since larger stars burn their fuel more quickly, the Sun would have burned out already had it been twice its size. Were it much smaller, it would give out so little heat that the Earth would be locked in a permanent freeze, and would be too cold for any form of life to survive.

solar mass

A solar mass is a figure, a unit of measure, used by astronomers to compare the size of other stars with our Sun. In this case, the Sun’s mass is used as the universal standard, and is counted as one solar mass.

The mass of the Sun is equal to:

1.989 x 1030 kg
4.376 x 1030 lbs
(or 333,000 Earth masses)

Therefore, if a star is said to be 5 solar masses in size, it is equivalent to:

1.989 x 1030 kg x 5


A solstice is an astronomical event that happens twice each year as the Sun reaches its highest or lowest excursion relative to the celestial equator on the celestial sphere. As a result, on the day of the solstice the Sun appears to have reached its highest or lowest annual altitude in the sky above the horizon at local solar noon. The word solstice is derived from the Latin sol (sun) and sistere (to stand still), because at the solstices, the Sun stands still in declination; that is, the seasonal movement of the Sun's path (as seen from Earth) comes to a stop before reversing direction. The solstices, together with the equinoxes, are connected with the seasons. In many cultures the solstices mark either the beginning or the midpoint of winter and summer. The day of the solstice is either the longest day of the year (in summer) or the shortest day of the year (in winter) for any place outside of the tropics.

Supernova Remnant

Supernova Remnant

The Sun

Our Sun

Telstar 1

Telstar 1


Space is so vast that astronomers have had to devise special units to keep their figures manageable. Their basic unit of distance is the lightyear - the distance light travels in one year, or about six trillion miles (6 followed by 12 zeros). Astronomers also use an even larger unit known as the parsec, which is the equivalent to 3.26 light-years.

supernova remnants

A rare celestial phenomenon involving the explosion of most of the material in a star, resulting in an extremely bright, short-lived object that emits vast amounts of energy. (Plural: supernovae, or supernovas.) The composite photo above shows the remnant of a supernova located in the Large Magellanic Cloud some 160,000 from Earth. The green/blue area of the bubble shows heated material detected by NASA's Chandra X-Ray Observatory. The glowing pink rim (optical data from the Hubble Telescope) is ambient gas being shocked by the blast wave from the supernova.

telstar 1

Telstar 1, the world’s first commercial communications satellite. It’s creation was a collaboration between AT&T, Bell Telephone Laboratories, NASA, the British General Post Office, and France’s PTT. The satellite’s mission was to improve and augment transatlantic communication, and it was launched into orbit on July 10th, 1962, aboard a Thor-Delta rocket. It was the first to successfully relay television pictures, telephone calls, and fax images. It was also the first to transmit live transatlantic television feed. Its sister satellite, Telstar 2, was launched on May 7th, 1963. Although both machines are now inoperative, they are still in orbit.

the sun

The pressure at the centre of the Sun is about 700 million tons per square inch. Enough to crush atoms, expose their nuclei, and allow them to smash into each other, interact, and produce the radiation that gives off light and warmth.

If the Sun suddenly stopped shining, it would take eight minutes for people on Earth to be aware of it.

The Sun is 30,000 lightyears from the Milky Way's centre and takes 225 million years to make one complete orbit around it.

what's big?

Compared to the Earth, the Sun is huge. However, the Sun is not a particulary big star, as stars go. Consider the case of Betelgeuse, a red supergiant in the constellation Orion. If Betelgeuse were in the Sun's position, it would engulf the orbits of Mercury, Venus, Earth and Mars. If it were possible to make a telephone call from one side to the other, your voice, travelling at the speed of light, would take half an hour to reach the other side of Betelgeuse, even if the call were routed straight through the star's centre. If the call were routed around the surface of the star, your voice would take an hour and a half to get through.

what's in a year?

One Earth year = 12 months = 52 weeks = 365 days = 8,760 hours = 525,600 minutes = 31,536,000 seconds.