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My friend told me that there is a black hole in the center
of the solar system and that because of that we will never even be able to leave
our solar system even if we tried! Is it true?
JOSEPH,
AGE 11, STOKE-ON-TRENT Answer: Your friend
is almost right. We think there is a black hole at the centre of our Galaxy, not
our Solar System. The Sun is at the centre of the Solar System and there is certainly
no black hole there. In fact a number of space craft are now heading on their
way out of our Solar System, the Voyager and Pioneer probes. If
there was nothing before the big bang, where did the matter come from in the big
bang?
KYLE, AGE 15, GOBLES, MICHIGAN Answer:
What a good question. There are many answers to this, some of
which are somewhat complicated to explain so I'll pick one of the easier ones.
One idea explains that not only space, but time
was also made when the Universe formed in the explosion we call the Big Bang.
If time was made at the Big Bang, then time didn't exist before it so it's somewhat
meaningless to ask what happened before! So that matter didn't actually have anywhere
to come from! Seem a strange answer? Think about
this though. If you got in a car with a compass and headed north, eventually you
would reach the North Pole (ignoring the fact of all the water and snow between
here and there). Anyway, when you get to the North Pole, you have reached the
most northerly point on the Earth, there is nowhere further north! In
the same way, one theory says that there is no time before the big bang, you are
at the very beginning! Hard to get your head round that one! How
big is the solar system?
AURELIE, AGE 9, OTTAWA Answer:
The edge of our Solar System is found at a place called the heliopause and is
thought to be about 23 billion kilometers from the Sun. This means that the Universe
is 46 billion kilometers from one side to the other. That's pretty big. Can
black holes be a time machine?
SOFIA,
AGE 10, COLOMBIA Answer:Black
holes themselves cannot be used as time machines. If they were to join up to form
wormholes (we have not found a wormhole yet, they are just theoretical) then the
wormholes could be used as time machines. We would need to learn a lot more about
them though before we could. Yesterday I found
something really strange written in the Egyptian news. It says that the new planet,
Sedna, will be hitting the Earth in the year 2036. I just want to know if this
information is right or not because I think it would be a major disaster. Thanks.
HUSSEIN, CAIRO, EGYPT Answer:
There is no scientific evidence that suggests Sedna
will hit the Earth in 2036 or any other year. Why
does Earth have seasons?
ARNELL, AGE 11, KITCHENER Answer:
The Earth has seasons because it is tilted at an angle. Imagine the Sun sitting
in the middle of a huge piece of paper. The Earth moves around the Sun once every
year along the sheet of paper in a path that is like a squashed circle. The
Earth also spins around an axis, like a bike wheel and takes one day to do that.
Now, the axis that the Earth spins around does not point straight up and down,
its tilted over. This means that when the top half
(the northern half) of the Earth points to the Sun, we get summer and at the same
time, the bottom half (the southern half) is pointing away from the Sun and gets
winter. My question is relatively basic but I
do need some clarification. I was always under the impression that a light year
is the distance light travels within a year (6 x 10/12). However,
recently I have come across a reference book that suggests that one light year
represented by this equation is only 6 billion miles. Do
astronomers reflect 6 billion miles as a light year or 6000 billion miles as a
light year? Your answer is very important to me, and I would appreciate your help
in this.
DAVID, BRISBANE, AUSTRALIA Answer:
The confusion arises not in the definition of the length of a light year but
instead in the definition of a billion. The British
billion is a million million (1 followed by 12 zeros) whilst the American billion
is a thousand million (1 followed by 9 zeros). Convention
in science is still a little uncertain about this but the trend is toward the
American version. Most astronomers will tell you that a light year equals approximately
6 thousand billion miles. Can you see artificial
satellites with the naked eye?
ROSS, SAUNDERSFOOT Answer:
It is very easy to see satellites with the naked eye. Just look out on any
dark clear night and you will sometimes see lights steadily moving across the
sky. Check out (the 成人论坛 is not responsible for the content of external websites) and it will
tell you when you can see satellites and even the International Space Station.
What is a fireball?
LAETITIA,
AGE 11, ARIZONA Answer: A fireball
is just a very bright meteor! What's a meteor? A meteor is a piece of rock or
dust that falls through the atmosphere of the Earth. As
it falls, it gets hotter and hotter and starts to glow. Really big pieces of rock
glow brighter and we see these as fireballs. Sometimes, they can be so bright
that they will cast shadows. How big is the universe?
ELENAR, EDINBURGH Answer:
The Universe goes on forever and ever; we say that the Universe is infinite.
Why is it not usual to express the earth-moon
distance in astronomical units?
JOYCE Answer:
An astronomical unit is equal to the average distance between the Sun and
Earth (150 million km or 93 million miles). The distance to the Moon is on average
380,000 km. That's equal to about 0.0025 astronomical
units. The answer to your question is that it's just easier to work with in kilometres
rather than astronomical units as the units are too big. It's a bit like measuring
your height in kilometres rather than metres. 听 Read
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