Status Updates From The Star Guide: Learn How T...

"Only Ceres, Pallas, Vesta and a few other asteroids are roughly spherical in shape. The others are irregular-shaped lumps, looking rather like huge potatoes. From the way they reflect light, asteroids appear to be of three main kinds. Some are made up mainly of rock, some mainly of metal and others a mixture of the two" (154).

"The four terrestrial (Earth-like) planets have only three moons between them, compared with more than 130 for the four gas, giant planets" (150).

"Mars has an atmosphere like Earth, though it is very much thinner, with only about one-hundredth the pressure of Earth's atmosphere, and the main gas present is carbon dioxide" (144).

"...all lunar rocks...[are] volcanic" (134).

"The sprawling Oceanus Procellarum occupies much of this [SW] quadrant, covering an area of around 2 million square miles...This is over half as big again as the Mediterranean Sea on Earth. At its southern edge, Oceanus Procellarum merges into Mare Humorum and, through Mare Cognitum, into Mare Nubium" (130).

"Maria cover the best part of the near side of the Moon, but are strangely absent on the far side. Largest by far is the sprawling Oceanus Procellarum, the Ocean of Storms. It merges in the north with the largest circular mare, Mare Imbrium, the Sea of Showers" (126).

"Compared with Earth, the Moon is a small body. Its diameter is only 2,160 miles (3,476 km), or about a quarter the size of Earth. This is actually extraordinarily large for a satellite in relation to the size of its parent planet. This is why astronomers sometimes consider Earth-Moon to be a double planetary system" (122).

"...the Sun...lies on average about 93 million miles (150 million km) away from Earth, a distance known as the astronomical unit (AU). As stars go, it is relatively small, with a diameter of about 865,000 miles (1,390,000 km). It gives off a yellowish light. Astronomers classify it as a yellow dwarf" (118).

"Aldebaran, Alpha (a) Tauri, is easy to find because it is in line with the three stars that make up Orion's Belt - and the Pleiades lies farther away along the same line" (114).

"The Andromeda Galaxy, M31, is one of the foremost objects in the whole night sky. It is a spiral galaxy, like our own in structure, but much bigger. With a diameter of around 150,000 light years, it measures half as big again as our own Galaxy and could contain as many as 400 billion stars. It is the largest galaxy by far in our local galaxy cluster...of about 30 galaxies" (108).

"The most impressive variable is Chi (x) in the swan's neck. At maximum, Chi reaches 3rd-magnitude and rivals nearby Eta (h) in brightness. But it falls below 14th-magnitude at minimum, beyond small telescope range, over a period of 407 days. It thus displays one of the greatest brightness changes among variables we know" (102).

"Three brilliant stars appear high in the sky in the Northern Hemisphere, making up the celebrated Summer Triangle. Brightest is Vega in Lyra, which forms the triangle with Deneb in Cygnus and Altair in Aquila" (96).

"At a distance of some 50 light-years, this [The Virgo Cluster] is the closest big cluster to us. It may contain as many as 3,000 galaxies in all.

"The third largest constellation, Ursa Major, is the most familiar northern constellation because it contains the conspicuous star pattern known as the Big Dipper, or in Europe, as the Plow" (84).

"Orion, the most magnificent constellation in the heavens; straddling the celestial equator, Orion is equally familiar to observers in both the Northern and Southern Hemispheres. Its pattern of bright stars is distinctive and can readily be visualized as the figure of a mighty hunter, with a club raised ready to strike in one hand, and a shield in the other" (78).

"Cassiopeia is an unmistakable constellation, with its brightest stars forming a distinctive W-shaped pattern. It lies far north, on the other side of Polaris, the Pole Star, from Ursa Major" (70).