Planets around other Stars

Did you know that about 200 planets have been discovered around distant stars? The first planet found to be orbiting a star like our Sun was announced in 1995. Since then astronomers have continued to find new planets outside of our solar system, at a rate of more than one new planet every month!

Artist's concept of a rocky planet in orbit around a distant star.

The star and its planet orbit around each other. The planet moves in a wide orbit, while the star just appears to wobble slightly. By measuring the Doppler shift of the light coming from the star, scientists can detect the tiny motion caused by the planet. Most of the distant planets were discovered this way.

If we are lucky, some of the planets can pass in front of their star. This blocks out some of the light that we usually see from the star, briefly making it dimmer. It's like a solar eclipse, but the planet only covers a small part of the star. Only a few planets outside our solar system pass in front of their stars.

All of the distant planets are too far away to see directly. We can only see their effect on the star that they orbit.

Strange Stuff In Space

There is some pretty strange stuff in space. Things which are unlike anything that anyone sees every day on Earth. Things that challenge our ideas about the Universe. Things that are just so weird that even astrophysicists don't know what they are.

The doomed star Eta Carinae, it is blowing itself apart before it finally goes supernova

When stars die they go out in many different ways. When average mass stars, like our sun, die they go by throwing off their outer layers and leaving behind a White Dwarf. When very massive stars die they often blow themsleves apart in a huge explosion called a Supernova. Depending on how massive a star was that went supernova, a Neutron Star or a perhaps a Black Hole may be left behind as a monument to its former glory.

There are still stranger things in space. Not very long ago astronomers were baffled by the mystery of Quasars. These objects look like stars but are much farther away than stars in our galaxy and they are much more luminous than entire galaxies.

There is also a phenomenon (no, not John Travolta) that has caused much excitement and wonder among astronomers called Gravitational Lensing. This is where massive objects, like galaxies and galaxy clusters, actually bend light like a lens, using gravity! Is that wacky or what!?

One of the strangest things in space is the mystery of Gamma Ray Bursts. These are what seem to be random bursts of gamma rays, you know the radiation that transformed Bruce Banner into the Incredible Hulk. They come from every direction in the sky, they never repeat, and they may indicate the most energetic processes ever seen.

Top 10 Pieces of Evidence For Extra-Terrestial Life

If you are looking for intelligent life beyond our planet here are 10 controversial pieces of evidence for extraterrestrial life:

1. 1976, The Viking Mars landers detect chemical signatures indicative of life

2. 1977, The unexplained extraterrestrial “Wow!” signal is detected by an Ohio State University radio telescope

3. 1996, Martian “fossils” are discovered in meteorite ALH80041 from Antarctica

4. 2001, A more rigorous estimate of the “Drake equation” suggests that our galaxy may contain hundreds of thousands of life-bearing planets

5. 2001, The red tinge of Jupiter’s moon Europa proposed to be due to frozen bits of bacteria, which also helps explain the mysterious infrared signal it gives off

6. 2002, Russian scientists argue that a mysterious radiation-proof microbe may have evolved on Mars

7. 2002, Chemical hints of life are found in old data from Venus probes and landers. Could microbes exist in Venusian clouds?

8. 2003, Sulphur traces on Jupiter’s moon Europa may be the waste products of underground bacterial colonies

9. 2004, Methane in the Martian atmosphere hints at microbial metabolism

10. 2004, A mysterious radio signal is received by the SETI project on three occasions - from the same region of space

Classification of Asteroids

Asteroids are classified into a number of types according to their spectra (and hence their chemical composition) and albedo:

• C-type, includes more than 75% of known asteroids: extremely dark (albedo 0.03); similar to carbonaceous chondrite meteorites; approximately the same chemical composition as the Sun minus hydrogen, helium and other volatiles;
• S-type, 17%: relatively bright (albedo .10-.22); metallic nickel-iron mixed with iron- and magnesium-silicates;
• M-type, most of the rest: bright (albedo .10-.18); pure nickel-iron.
• There are also a dozen or so other rare types.

Because of biases involved in the observations (e.g. the dark C-types are harder to see), the percentages above may not be representative of the true distribution of asteroids. (There are actually several classification schemes in use today.)

There is little data about the densities of asteroids. But by sensing the Doppler effect on radio waves returning to Earth from NEAR owing to the (very slight) gravitational tug between asteroid and spacecraft, Mathilde's mass could be estimated. Surprisingly, its density turns out to be not much greater than that of water, suggesting that it is not a solid object but rather a compacted pile of debris.

Asteroids are also categorized by their position in the solar system:

• Main Belt: located between Mars and Jupiter roughly 2 - 4 AU from the Sun; further divided into subgroups: Hungarias, Floras, Phocaea, Koronis, Eos, Themis, Cybeles and Hildas (which are named after the main asteroid in the group).
• Near-Earth Asteroids (NEAs): ones that closely approach the Earth
  • Atens: semimajor axes less than 1.0 AU and aphelion distances greater than 0.983 AU;
  • Apollos: semimajor axes greater than 1.0 AU and perihelion distances less than 1.017 AU
  • Amors: perihelion distances between 1.017 and 1.3 AU;
• Trojans: located near Jupiter's Lagrange points (60 degrees ahead and behind Jupiter in its orbit). Several hundred such asteroids are now known; it is estimated that there may be a thousand or more altogether. Curiously, there are many more in the leading Lagrange point (L4) than in the trailing one (L5). (There may also be a few small asteroids in the Lagrange points of Venus and Earth (see Earth's Second Moon) that are also sometimes known as Trojans; 5261 Eureka is a "Mars Trojan".)

Between the main concentrations of asteroids in the Main Belt are relatively empty regions known as the Kirkwood gaps. These are regions where an object's orbital period would be a simple fraction of that of Jupiter. An object in such an orbit is very likely to be accelerated by Jupiter into a different orbit.

Asteroids

The first asteroid to be discovered, Ceres, is the largest asteroid known to date and is now classified as a dwarf planet. All others are currently classified as small solar system bodies. The vast majority of asteroids are found within the main asteroid belt, with elliptical orbits between those of Mars and Jupiter. It is thought that these asteroids are remnants of the protoplanetary disc, and in this region the accretion of planetesimals into a larger planet or planets during the formative period of the solar system was prevented by large gravitational perturbations by Jupiter. Some asteroids have moons or are found in co-orbiting pairs known as binary systems.

253 Mathilde, a C-type asteroid.

Asteroids, also called minor planets or planetoids, are a class of astronomical objects. The term asteroid is generally used to indicate a diverse group of small celestial bodies in the solar system that orbit around the Sun. 'Asteroid' (Greek for "star-like") is the most commonly used word in the English literature for minor planets, which has been the term preferred by the International Astronomical Union; some other languages prefer planetoid (Greek: "planet-like"), because it more or less describes what they are. In late August 2006, the IAU introduced the term "small solar system bodies" (SSSB), which includes most objects thus far classified as minor planets, as well as comets. At the same time they introduced the term 'dwarf planet' for the largest minor planets. This article deals specifically with the minor planets that orbit in the inner solar system (roughly up to the orbit of Jupiter). For information on other types of objects, such as comets, Trans-Neptunian objects, and centaurs, see Small solar system body.

Comets

Unlike the other small bodies in the solar system, comets have been known since antiquity. There are Chinese records of Comet Halley going back to at least 240 BC. The famous Bayeux Tapestry, which commemorates the Norman Conquest of England in 1066, depicts an apparition of Comet Halley.

As of 1995, 878 comets have been cataloged and their orbits at least roughly calculated. Of these 184 are periodic comets (orbital periods less than 200 years); some of the remainder are no doubt periodic as well, but their orbits have not been determined with sufficient accuracy to tell for sure.

Comets are sometimes called dirty snowballs or "icy mudballs". They are a mixture of ices (both water and frozen gases) and dust that for some reason didn't get incorporated into planets when the solar system was formed. This makes them very interesting as samples of the early history of the solar system.

When they are near the Sun and active, comets have several distinct parts:

• nucleus: relatively solid and stable, mostly ice and gas with a small amount of dust and other solids;
• coma: dense cloud of water, carbon dioxide and other neutral gases sublimed from the nucleus;
• hydrogen cloud: huge (millions of km in diameter) but very sparse envelope of neutral hydrogen;
• dust tail: up to 10 million km long composed of smoke-sized dust particles driven off the nucleus by escaping gases; this is the most prominent part of a comet to the unaided eye;
• ion tail: as much as several hundred million km long composed of plasma and laced with rays and streamers caused by interactions with the solar wind.

Comets are invisible except when they are near the Sun. Most comets have highly eccentric orbits which take them far beyond the orbit of Pluto; these are seen once and then disappear for millennia. Only the short- and intermediate-period comets (like Comet Halley), stay within the orbit of Pluto for a significant fraction of their orbits.

After 500 or so passes near the Sun off most of a comet's ice and gas is lost leaving a rocky object very much like an asteroid in appearance. (Perhaps half of the near-Earth asteroids may be "dead" comets.) A comet whose orbit takes it near the Sun is also likely to either impact one of the planets or the Sun or to be ejected out of the solar system by a close encounter (esp. with Jupiter).

By far the most famous comet is Comet Halley but SL 9 was a "big hit" for a week in the summer of 1994.

Meteor shower sometimes occur when the Earth passes thru the orbit of a comet. Some occur with great regularity: the Perseid meteor shower occurs every year between August 9 and 13 when the Earth passes thru the orbit of Comet Swift-Tuttle. Comet Halley is the source of the Orionid shower in October.

Many comets are first discovered by amateur astronomers. Since comets are brightest when near the Sun, they are usually visible only at sunrise or sunset. Charts showing the positions in the sky of some comets can be created with a planetarium program.

Advanced extraterrestrial alien civilization

It is estimated that terrestrial technologies can detect one in hundred asteroids and comets that is in a collision course.

Interestingly, even if we in the earth find some incoming asteroids that will collide with the earth, little we can do. Take the example of asteroid 1950AD. It is about three quarters of a mile in length. It will collide with earth in year 2880. The collision will cause an explosion equivalent to 100,000 megaton. The human race will get wiped out. Knowing this very well, we can do little to protect us. A nuclear missile if sent out to encounter the asteroid will make a zillion scattered pieces and the earth will get bombarded zillion times in different place and the effect will be even worse. We do not have the power to vaporize this asteroid with the entire nuclear arsenal in the earth. A close vicinity nuclear explosion may deflect it if the asteroid is of high density and we know about the asteroid at least two years before it impacts on the earth. There are other evolving theories to neutralize the incoming asteroids but nothing has been tested. On top of that we can detect one in hundred such crashing bodies (comets and asteroids) coming towards us. Many scientists believe we just do not have the technologies to protect us.

But case after case in different parts of the world, there are evidences that comets and asteroids have been neutralized either through deflection or explosion before hitting the earth. Who is doing the protection job deflecting and neutralizing asteroids and comets before they are hitting the earth?

According to some scientists, the asteroid belt is disturbed and many asteroids are colliding among themselves. This causes deflection of these asteroids into the inner solar system with possible collision paths with the earth. If any one of these hit the earth, we are history. We can detect very few of these asteroids. As a matter of fact in many cases we realized that these asteroids and comets have missed the earth by a hair in the cosmic scale.

According to scientists there is some advanced alien civilization that is protecting the earth for a long time and is determined not to let these asteroids collide with earth. If you have a doubt, they suggest look at moon surface that have received zillion asteroids and comets and the moon’s dead surface bear the history in every inch of its surface. No one is protecting the moon or mars for whatever reason.

Energy needed to vaporize a comet or asteroid to protect the earth is far larger than the combined aggregation of all nuclear bombs in different parts of the earth. The extraterrestrial alien civilization is using radiation energy tapped from the Hyperspace through the fermions to neutralize the asteroids and comets.

Scientists getting a clue from this are rapidly looking at the Hyperspace to tap endless radiation energy to neutralize incoming comets and asteroids. This radiation energy can also provide enormous alternative fuel that is cheap, have no nuclear waste and above all intense to perform whatever we want to do.