We have always been interested in the moon. 2000 years ago people already knew it moved around the earth and where it would be in the sky at different times of the year. At that time, everything about the moon was learned by watching it carefully in the sky.

    When scientists could use telescopes to study the moon more closely, their ideas began to change. They could see the moon was made of rocks. Most scientists thought moon rocks would be different from those on Earth. This was because they believed the moon had once been a planet that had been caught in the earth's gravity (引力) millions of years earlier.

    In 1969 moon rocks were finally brought to the earth and studied. Much to their surprise, scientists found that, except for water, the moon and the earth were made of the same things. Once again new ideas were needed for this new information.

    After years of study, most scientists now think that the moon was once part of Earth. They believe very early in its history, maybe 4 million years ago, something about the size of Mars hit Earth. This sent billions of rocks into space around our planet. These rocks slowly joined together and after many years became the moon.

    However, in the future, even though our ideas about the moon may change again, we will still be interested in it.

    The idea of being able to walk on water has long interested humans greatly. Sadly, biological facts prevent us ever accomplishing such a thing without artificial aid-we simply weigh too much, and all our mass pushes down through our relatively small feet, resulting in a lot of pressure that makes us sink.

    However, several types of animals can walk on water. One of the most interesting is the common basilisk Basilicus basilicus, a lizard(蜥蜴) native to Central and South America. It can run across water for a distance of several meters, avoiding getting wet by rapidly hitting the water's surface with its feet. The lizard will take as many as 20 steps per second to keep moving forward. For humans to do this, we'd need huge feet that we could bring up to our ears in order to create adequate "hitting."

    But fortunately there is an alternative: cornflour. By adding enough of this common thickening agent to water (and it does take a tot), you can create a "non-Newtonian" liquid that doesn't behave like normal water. Now, if the surface of the water is hit hard enough, particles(粒子) in the water group together for a moment to make the surface hard. Move quickly enough and put enough force into each step, and you really can walk across the surface of an adequately thick liquid of cornflour.

    Fun though all this may sound, it's still rather messy and better read about in theory than carried out in practice. If you must do it, then keep the water wings handy in case you start to sink and take a shower afterward!

    Have you got an eReader? Are you thinking of getting one? We asked some eReaders owners to give us their opinions.

    There are many things that people like about eReaders. "eReaders are really light, weighing less than most paperbacks," said Nathan Jones, a market researcher. "You can hold the book and turn the pages with one hand. An eReader is definitely more comfortable to read in bed or if you're lying on a sofa, plus mine's got a light so I can read in bed at night without disturbing my partner." Another big advantage is that you can store hundreds of books on them. "eReaders are perfect for travel," said Kiera Smith. "You can have lots of books in one device, instead of carrying loads of books in your luggage." The search functions are also popular. "You can look for a character by their name or for a place just by typing in the word. That's really useful," said Megan Malone, a sales executive.

    One user liked the function for increasing font size. "I've got poor eyesight," explained Harvey Callaghan, an engineer. "But the eReader is perfect for me as I can increase the font size." And Jennifer Saunders said, "I like eReaders because they're ecological. If we buy an ebook, we're helping to save trees as they don't use paper. Also, my eReader is solarpowered, so it only uses renewable energy." Best of all is the availability of hundreds of free books online. "Project Gutenberg has millions of titles and they're all free to download," said another user.

    One of the biggest complaints is that you can't find certain titles. "Many books are simply not available in electronic form," said Daisy Madison, an estate agent. If you want a specific book, one that is older, perhaps, or not a bestseller, it won't be available – at least, that was my experience."

    Others complained about the small delay in turning pages. "The gap between pressing the 'next page' button and the screen showing the page is really annoying," said Joel Bray, a shop assistant. "Also, you can't flick between pages so easily."

So, what do you think?