What if aliens were visited by aliens

In , NASA launched the Kepler space telescope, which was designed to search for exoplanets using a different method. During the last transit of Venus, in , viewers on Earth could watch a small black dot creep across the sun. Kepler measured variations in the brightness of more than a hundred and fifty thousand stars in the vicinity of the constellations Cygnus and Lyra.

By , it had revealed the existence of a thousand exoplanets. By the time it stopped operating, in , it had revealed sixteen hundred more. This is the average number of rocky, roughly Earth-size planets that can be found orbiting an average sunlike star at a distance that might, conceivably, render them habitable. Since there are at least four billion sunlike stars in the Milky Way, this means that somewhere between 1. Kershenbaum argues that the key to understanding cosmic zoology is natural selection.

From this premise, Kershenbaum says, it follows that life on other planets will have evolved, if not along the same lines as life on this planet, then at least along lines that are generally recognizable. On Earth, for instance, where the atmosphere is mostly made of nitrogen and oxygen, feathers are a useful feature. Assuming that there is, in fact, alien life out there, most of it seems likely to be microscopic. This, in his view, opens up quite a can of interstellar worms.

Will they accord us whatever rights, if any, they grant their little green or silver or blue brethren? Still, Fermi reckoned that Earth was a fairly typical planet revolving around a fairly typical star. There ought, he reasoned, to be civilizations out there far older and more advanced than our own, some of which should have already mastered interstellar travel. Is this a natural object of the type that we suspect to be extremely common in the Milky Way, or is it aliens?

Aliens raise a whole set of supplementary questions who, why, from where? A not quite completely understood acceleration is not extraordinary evidence, as there are many plausible explanations for it. Yet another check is the often sluggish but usually reliable peer-review system, in which scientists publish their findings in scientific journals where their claims can be assessed and critiqued by experts in their field.

This does not mean that we should not look for aliens. A lot of time and money is being devoted to researching them. Other interesting targets are the moons of Jupiter and Saturn. In the next five years, we will also have the technology to search for alien life on planets around other stars exoplanets.

Both the James Webb Space Telescope due to launch in , and the European Extremely Large Telescope due for first light in will analyse exoplanet atmospheres in detail, searching for signs of life. It is premature to contemplate a global policy long before it is required. How much advance warning will we have? That depends on the size of the vehicle used by the ETs. Even without generating artificial light, any alien spacecraft would reflect sunlight.

The Pan-STARRS observatory in Hawaii can detect reflected sunlight from objects bigger than a few hundred feet, the scale of a football field, that pass within the orbit of the Earth around the sun. The object showed many anomalous properties that made it different from any natural comet or asteroid that we had witnessed before in the solar system, allowing for the possibility that it is a product of alien technology, as discussed in my new book, Extraterrestrial.

If it is, the question arises as to whether it is likely to be a probe intended to spy on us. Most stars formed billions of years before the sun, and the technological relics that their civilizations launched to space are probably too old to be functional.

We can retrieve more information about technological relics by taking close-up photographs or by searching on the surface of the moon or Mars for unusual objects that have collected there over the past billions of years. Are we the smartest kid on our cosmic block? There have been many, many projects since then.

One of the center's major initiatives was Project Phoenix, which scanned nearby, sun-like stars. Currently, the SETI Institute, in collaboration with other institutes, is working on a concept called the Allen Telescope Array, which has dozens of radio dishes in northern California.

In , the well-known physicist Stephen Hawking and many other researchers launched Breakthrough Listen , a project that will scan 1 million Milky Way stars and nearby galaxies for extraterrestrial life. While searches of alien messages aren't ongoing in space, there have been efforts to communicate with any beings that may come across our spacecraft.

The Pioneer 10 and 11 probes flew by Jupiter and in Pioneer 11 's case, Saturn to eventually make their way out of the solar system. Before their launches in and , respectively, a Pioneer plaque was mounted on board each spacecraft. It shows the form of the human body and where the Earth is located in the galaxy.

The twin Voyager probes launched in to examine the outer solar system. Voyager 2 reached interstellar space in , while Voyager 1 is still at the edge of the solar system.

Each of the spacecraft includes two golden records with sounds recorded on Earth, ranging from whale calls to music to the word "hello" in many languages. The record also has diagrams of the human body and where our solar system is located. Scientists also transmitted a radio message from the Arecibo Observatory in Puerto Rico in