In 1901, a remarkable inventor and scientist called Nicolas Tesla dreamt of communicating with inhabitants of other planets. He even believed that it would be possible to send a signal from Earth to Mars with the same accuracy as messages were being sent by wire from New York to Philadelphia.MIT researchers have taken a step towards Mr. Tesla’s dream by developing a tiny light detector that may allow for super-fast broadband communications over interplanetary distances.In another instance, a pioneering demonstration of communications between NASA’s Mars Exploration Rover Spirit and the European Space Agency (ESA) Mars Express orbiter succeeded. On February 6, while the Mars Express was flying over the area Spirit was examining, the Orbiter transferred commands from to Earth to the Rover and relayed data from the robotic Explorer back to earth.As far as communicating with creatures on other planets is concerned, we really do not know yet whether life exists in space. Yet, when the space probe Pioneer 10 was launched in 1972, it carried a picture greeting for any intelligent beings that might find it. A plaque on board the Pioneer 10, showed a picture of a man and woman and the sun as the centre of our civilization with 14 radiating lines emitting from it. It also depicted the symbol for the hydrogen atom which is called ‘the universal clock’, and our solar system, with the route of Pioneer marked on it.We do not know whether our message to another planet was ever seen by anyone …but we haven’t got a reply yet to our greeting!

The eclipses of the Sun and the Moon occur during new moon and full moon respectively. A solar eclipse does not occur at every new moon, because the Moon orbits in a plane which is inclined to the ecliptic, the plane of orbit of the Earth around the Sun.

The angle between the planes is about five degrees and hence the Moon can pass well above or below the Sun. The line of intersection of the planes is called the line of nodes.

There are only two points where the Moon’s orbit intersects the ecliptic plane. The nodes move along the orbit from west to east, going completely around the ecliptic in about 19years.

For an eclipse to occur, the Moon has to be near one of the nodes. This does not happen on all new moon and full moon days.

            Once in a Blue Moon… is a common way of saying not very often, but what exactly is a Blue Moon? It is the second Full Moon to occur in a single calendar month. The moon goes through one complete cycle every 29.5 days, but the solar calendar months are longer – usually 30 or 31 days. This makes it very unlikely that any given month will contain two Full Moons, though it does sometimes happen: If you have a full moon on the first or second day of the month, a second full moon will occur at the end of the month.

The well-known Metonic cycle of lunar phases is 19 years long. During this time, there are 235 lunar months, and hence 236 Full Moons. There are also 228 calendar months, so at least 8 of those months must have seen two Full Moons. So, we can define Once in a Blue Moon as a probability: 8 chances in 228, or about 3.5 per cent!

Thus every 19 years or so a single year will offer two Blue Moons. In 1999, when the next double-Blue-Moon bonanza rolls around, February will have no full moon, but January and March will both boast a full moon and a bona fide Blue Moon. There are several other meanings ascribed to the term “blue moon” (the most common being “an uncommon event”) According to  reports, when the Indonesian volcano Krakatoa exploded in 1883, its dust turned sunsets green and the moon blue all around the world for the best part of two years. In 1927, a late monsoon in our country set up conditions for a blue moon.

Even by the 19th century, it was clear that although visually blue moons were rare, they did happen from time to time. So the phrase “once in a blue moon” came about. It meant then exactly what it means today: that an event was fairly infrequent, but not quite regular enough to pinpoint.” Some of the recent/upcoming blue moons: January 31, 1999; March 31, 1999; December 30, 2001; July 31, 2004; June 30, 2007 and December 31, 2009.

            The stars seem to twinkle, because we see the stars through the ocean of air, the atmosphere. The twinkling is caused by differences in temperature in the air. Some layers of air hotter than others, and one layer is always swirling and moving through another. These different layers of air bend the star light in different ways, and at different angles. It is this passing through layers of air of different temperature that makes the light of the stars unsteady.

The stars near the horizon seem to twinkle much more than those high in the sky. This is because the light of these stars has to travel a longer path through a thicker layer of atmosphere, and thus has more chance to become disturb. Sometimes the stars twinkle much more than they do at other times. This is true because at sometimes the atmosphere is not so still as it is at other times, or because there is not such a variation of temperature within its different layers.

Planets do not twinkle, ordinarily, but seem to shine with a steady, unwavering light. Even through telescopes, the biggest stars appear simply as tiny points of light, while the planets show very definite discs and surfaces. Hence, more rays come to us from the surface of a planet than from the surface of a star. The light from the planets does not waver as much as that from the stars the wavering of one light is counteracted by the wavering of another ray in another direction. If one could climb up above the atmosphere surrounding the earth and then look at the stars, he would see them shining with a clear and steady light, with no suspicion of twinkling.

When a ray of light travels from one optical medium to another, there is a deviation from its original path. This phenomenon is called refraction. If a light ray travels from an optically rarer medium to an optically denser medium, the light ray always bends towards the normal. The normal is nothing, but an imaginary line drawn at the point of incidence.

 The atmosphere of earth consists of a number of parallel layers of air with varying densities. Such that, the densest layer of air is near the surface of the earth. Layers with decreasing order of densities occupy the successive layers, and the top most layers are the least dense layer.

Light rays originating from a star (say x), pass through the atmosphere, before reaching the observer. In doing so, the light bends towards the normal, thereby deviating from its path slightly. This deviation takes place each time the light ray travels from a less dense layer to a denser layer. Finally when the refracted rays reach the observer, it traces a straight line path. To the observer, it appears to come from a pointy, which is higher in horizon. The pointy only gives an apparent position of the star.

The parallel layers of air are not stationery, but constantly intermingle with one another, thereby rapidly changing their densities. These changes give rise to the change in the apparent position of the star. As long as the star is within the line of sight of the observer, it is visible, but when the image falls outside the line of sight it is no longer visible. These changes in the apparent position of the star give rise to the “blinking” or “twinkling” effect.

Planets on the other hand are close to the earth, as compared to the stars. Their apparent position also changes with the changes in the densities of the air layers. But, the size of their apparent image being fairly large, seldom falls outside the line of sight of the observer. Hence they do not blink.

            The time of rising and setting of any celestial body is a function of its position in the sky defined by right ascension and declination in the celestial coordinate system, position of the observer on the Earth and the zenith distance of the body adopted to define the phenomena. Due to Earth’s motion in its orbit around the Sun, the geocentric right ascension of the Sun increases at the rate of 1 degree per day with slight variation during the course of the year.

            However, the declination of the Sun varies from about 23.5 degree south in winters to 23.5 degree north in summer during the course of the year. The rate at which the declination varies changes very much from about 0.4 degree on vernal equinox to 0 degree on summer and winter solstices. The longest day occurs in the Northern hemisphere when the declination of the sun is maximum north on summer solstice.

Around the time the daily rate of change in declination goes through zero value. Therefore, around this time the rising and setting times are affected mainly due to change in right ascension which can be about 1/2 degree from sunrise to sunset. It is for this reason that earliest sunrise does not coincide with latest sunset for a given place.

The difference is more pronounced for places in lower latitudes on earth over which the diurnal path of Sun is at a greater inclination to the horizon and its motion in right ascension takes it more to the East, away from the horizon. 

Yes, the sun too rotates about its axis. But unlike the earth, which has rotation period of one day, the sun has a ‘differential rotation’.

 That is, all parts of the sun do not have the same period of rotation. The period of rotation near its equator is 26.9 days, at sun spot zone (16 degrees north) it is 27.3 days and at the ole it is 31.1 days (syndical).

The sun’s enormous core temperature of 15 million degree Kelvin and a surface temperature of 6,000 degree Kelvin leave all its constituents in a high pressure, gaseous state called plasma. For the purpose of certain calculations, the top and the bottom ends of the visible sphere of the sun are designated as north and south poles respectively.

Photographs are taken daily and the movements of the spots, filaments and plages are observed for various latitudes and longitudes, for a long period of time. From this, the sidereal rotation period is calculated. The reason behind this phenomenon is still a puzzle to solar physicists.

            The planets are believed by many authorities to have coalesced from a disk-shaped cloud of gas early in the evolution of our solar system, beginning roughly 5 billion years ago, said Joe Rao, Lecturer at the Hayden Planetarium of the American Museum of Natural History in New York.

            “We believe that the sun and planets evolved from a huge, swirling cloud of gas and dust that  condensed over a time span of hundreds of millions of years”, Rao said. “This gas cloud was very likely in the shape of a disk, and when the planets came to be within this cloud, they pretty much all formed basically along the same plane.”

There is a notable exception the tiny planet Pluto, which has an orbit that is tipped as much as 17 degrees to the plane of the solar system, Rao pointed out. It has been hypothesized that Pluto might be everything from an escaped moon of Neptune to a special type of minor planet or asteroid. The anomalous orbit of Pluto was one of the reasons for the great debate earlier this year concerning Pluto’s exact status as a member of the solar system, Rao said.

We know that animals can communicate with each other. They do so through their body language, facial expressions, eye movements and sounds. Dolphins communicate through whistles and squeaks that form of a language their own. When dogs bark or a cat meows, it is telling another dog or cats something…Only we cannot understand what it is. Animals can also understand our language to some extent. It you train a dog properly; it will sit when you say ‘Sit’ and fetch a stick that you throw when you say ‘fetch’. Dolphins in fact can understand quite complex commands.Unfortunately, we have not yet mastered the art of communicating with other species on this planet. Some people seem to intuitively know what an animal is trying to communicate, but for the most part we do not have a clue about what animals are thinking. We may realize from their body language that they are going to attack, or that they are happy, but we cannot understand the sounds they make…yet! Maybe, in the future, we will develop computers that will be able decipher their grunts and growls, squeaks and whistles…and maybe we will learn to 

The thud of the newspaper falling on your doorstep is a familiar sound every morning. But soon it may become a thing of the past. In the future, you may be printing your newspaper at home!There is no doubt that books and newspapers will change considerably in the future. News printers will become so common that each family may have a new printer at home. This news printer will not only print the newspaper every morning, but will also send messages from one home to another. So, in the future, the sight of a newspaper boy, cycling through rain and storm to bring your family its morning paper, will be only a fond memory