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Discover the space walker in you
It depends on how much you know about space. Maybe you’ve just seen one too many sci-fi flicks. Or you’re really the one who keeps tabs on what Hubble focuses on. How space-savvy you are? Check for yourself.
1. Which is larger?
(a) A galaxy
(b) A solar system
(c) A universe
2. How many stars are in our solar system?
(a) 1
(b) More than 437,352
(c) Too many to count
3. Which is closer to Earth, the Sun or the Moon?
(a) Sun
(b) Moon
(c) They are about the same distance from Earth
4. How many known planets revolve around the Sun?
(a) 3
(b) 9
(c) 10
5. What planet’s orbit takes it farthest from the Sun?
(a) Pluto
(b) Mars
(c) Neptune
6. Which celestial body has a greater diameter, the Earth or the Moon?
(a) Earth
(b) Moon
(c) Neither. In an amazing coincidence, the Earth and the Moon have exactly the same diameter!
7. Compared to the largest stars and the smallest stars, the Sun is:
(a) A large star
(b) A middle-sized star
(c) A small star
8. How many constellations are there in the sky?
(a) 12
(b) 43
(c) 88
9. Which planet’s status as a planet has been questioned?
(a) Pluto
(b) Venus
(c) Saturn
10. In the Earth’s sky, which appears larger?
(a) The Sun
(b) The Moon
(c) Neither. In an amazing coincidence, the Sun and Moon appear to be the same size in the Earth’s sky!
ANSWERS
Believe it or not, most of the readers were unable to answer all the answers correctly. The correct answers are:
1. C — A universe. The universe is the largest thing there is. It is everything. A galaxy is an ensemble of hundreds of millions of stars — astronomers estimate that there are about 125 billion galaxies in the universe. A solar system is a group of celestial bodies orbiting a star.
2. A — The Sun. It is the one and only star in the Earth’s solar system.
3. B — The Moon. It is much closer to Earth than the Sun. The average distance of the Moon from Earth is 238,857 miles. The average distance of the Sun from Earth is 93 million miles!
4. B — Nine. Nine known planets revolve around the Sun in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.
5. A — Pluto. Its orbit takes it farther from the Sun than any other known planet. Pluto has an elliptical orbit, so sometimes it is actually closer to the Sun than the next most distant planet, Neptune. When Pluto is farthest from the Sun, the distance between the two is 4.6 billion miles. Pluto also has the highest average distance from the Sun: 3.7 billion miles.
6. A — Earth. It has a larger diameter than that of the Moon. Earth actually has two diameters: an equatorial diameter (around the equator), which is 7,926.42 miles, and a polar diameter (crossing the North and South poles), which is 7,899.83 miles. The diameter of the Moon is 2,160 miles.
7. B — A middle-sized star. The Sun is an average star — its size, age, and temperature fall in about the middle of the ranges of these properties for all stars. It is the closest star to Earth, which is why it appears to be so much bigger than other stars.
8. C — 88. Astronomers recognize 88 constellations — groupings of stars that form distinctive patterns — in the sky. The constellations are named after religious or mythical figures, animals, and objects.
9. A — Pluto. Many astronomers think Pluto may be an escaped satellite of Neptune, knocked into a separate orbit during the early days of the solar system. Other astronomers believe that Pluto is simply one of the most visible objects in the Kuiper belt, a ring of debris that orbits the Sun. Whatever Pluto’s origins, it probably will keep its planetary status—for historical and traditional reasons.
10. C — Neither. In an amazing coincidence, the Sun and Moon appear to be the same size in the Earth’s sky! The Sun’s diameter is about 400 times that of the Moon, but it is nearly 400 times farther away. The effect is that their disks appear to be the same size in the Earth’s sky. Because of this amazing coincidence, during a total solar eclipse, the Moon can appear to cover up the Sun exactly. — encarta.msn.com
Ten things you should know before you go into space
Space is a tricky place to travel, even for astronauts who know what they’re up against. Here are ten useful facts for the aspiring space traveller. The more you know, the further you’ll go.
1. The gravitational pull of a black hole is so strong that nothing—not even light—can escape from it. That’s why it’s black, or rather, has a complete absence of colour.
2. Major storms are common on Jupiter. Its most famous storm, the Great Red Spot, has been raging since telescopes were first aimed at the planet centuries ago.
3. Mars is home to the largest known volcano in the solar system, Olympus Mons. It is 26km high (almost twice as high as Earth’s Mount Everest) and covers an area about as large as the state of Arizona.
4. The surface temperature on Venus is extremely hot—about 462°C (864°F); hot enough to melt lead. To put this in perspective: lead melts at 328°C (662°F).
5. To reach outer space, you need to travel at least 80km beyond Earth’s surface.
6. The Voyager probes (launched in 1977) yielded some surprising information about Jupiter’s moons. The most surprising discovery was that Io is covered with active volcanoes spewing ice and sulfur compounds into space. Io was the first celestial body other than Earth found to be geologically active.
7. Comets are icy wanderers that populate the solar system’s outermost reaches. These “dirty snowballs” are chunks of ice and dust. When a comet ventures into the inner solar system, some of its ice evaporates.
8. In the vacuum of space, objects become intensely hot when exposed to the Sun and extremely cold when in the shadow of Earth or some other body.
9. The brightest star in the sky is Sirius. It is 51 trillion miles away from Earth, and is one of the closest stars to Earth. Another name for Sirius is Dog Star.
10. Neptune has the fastest winds in the solar system, reaching speeds of 2,000 km/hr. — encarta.msn.com
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