Why is the sky blue?
In the first approximation the skies on planet Earth are deep blue. Although it seems quite obvious (because we are used to it), it is not so at all. In fact, the sky over lunar surface is rather black, and the Martian sky photographed by numerous space probes is more or less red and yellow. So why the sky is almost always blue on Earth?
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What is the oldest known object in the Universe?
This question seems to be very simple, but in fact is as complex and dangerous as only a cosmological problem can be! First of all it requires a very careful defining of almost every word included: “is”, “the oldest”, “known”, “object” and finally “in the Universe”. Let’s start.
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How many stars can you see at night?
There are billions of stars just in our galaxy and it is estimated that in the visible Universe, there are about 200 – 300 billion large galaxies. It gives a HUGE amount of stars – approximately 10^24. But how many of them can we observe with the naked eye? Of course, directly we can only see the stars of our own galaxy, Milky Way. This is because of the large distance to other galaxies which we only observe as faint clouds in the sky. In fact, only few galaxies are visible to the naked eye in Earth’s sky, including famous Andromeda Galaxy M31 and both Magellanic Clouds. But using the powerful optical telescopes we can separate distant galaxies into individual stars.
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Is the Sun going to die?
Yes, it is. The Sun is only one of about 200 billion stars in our galaxy, Milky Way. Apart from holding the planet Earth, Sun is not exceptional and, like other celestial bodies, had a beginning and will have an end. But it will not take place anytime – the Sun still has about 5 billion years of life left.
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What are the rogue planets? Thinking about the planets we usually imagine globes orbiting other “suns”, or just other stars located somewhere in our galaxy. At this time (10 March 2014) we know 1771 extrasolar planets owned by about 1100 planetary systems, therefore exoplanets are not uncommon and their existence is obvious. Continue reading “What are the rogue planets?”
Does every galaxy have a black hole at the center? No, not every galaxy hosts a black hole, but the truth is that the vast majority of them actually do.
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Is there a dark side of the Moon?
What it looks like? Why we are not able to see it? Continue reading “Is there a dark side of the Moon?”
Why Do People Sneeze?
One of the main things we need to consider is…is…ACHOO! Sorry, we need…ACHOO!
Sneezes always seem to come upon us at the most inopportune times. Whether you’re in the middle of a business meeting, asking out that hot date, or carrying a huge tray of food, sneezes seem to follow their own schedule and not our own.
So what are sneezes and why do they happen? After all, ever person on the planet sneezes from time to time, usually twice in a row, and most animals do so as well. What’s behind this amazing, and often annoying, marvel of nature?
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Does the color red really make bulls mad?
The crowd goes quiet; you could hear a pin drop. The bull stamps its feet, and everyone holds their breath. Finally the bullfighter twirls his red cape about and the beast starts charging, rushing right for the bright red.
At the last instant the bullfighter swishes the cloth away and the bull charges right past him, angrier than ever, just as the crowd lets out a deafening roar.
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