Any extraterrestrial beings, aliens, who possess the capability of traveling to Earth will likely far surpass us in intelligence and be quite hostile.
Thoughts such as, "If you are stupid enough to challenge them, you will be taken out in three seconds," are the purview of people like Ridley Scott, director of several of the “Alien” series of movies. He believes that hundreds of alien species are out there on distant worlds and Earth's inhabitants should prepare for the worst whenever they decide to visit our planet.
Scott says that even though our movies often show how we plucky humans eventually find a way to defeat the terrifying aliens, don't expect a happy Hollywood ending when they come calling for real. Our best bet, Scott said, would be to "run for it."
Seth Shostak, the senior astronomer at the SETI Institute, disagrees, saying that Scott's information about such hostile and abundant aliens is off-base and unsupported. While our current knowledge of extraterrestrial planets tells us that potentially habitable exoplanets are quite common, and, therefore, we might assume intelligent life also to be common in the universe, that's a far leap from assuming they might actually come here.
First of all, Shostak says, any planet farther than 70 light years away would not have received any radio signals from us to indicate our existence. Even if more a distant civilization had the technological ability to detect the oxygen in our atmosphere, it's unlikely they'd send a heavily-armed armada “to look at what might amount to just a lot of bacteria.”
It's also unlikely aliens would come searching to supplement their diets. Their biochemistry is likely not compatible with ours. "To do that, they would have to know that we had something interesting within our bodies that they could metabolize, and their body chemistry would probably be very different from ours," Shostak said.
Earth formed 4.5 billion years ago, but our Milky Way galaxy is 12 billion years old. Planets far older than Earth orbit other stars and many intelligent species far older than humans might also exist. Chances are virtually certain that any alien civilization that might show up here is millions or even billions of years technologically superior to us. Even though Shostak discounts the likelihood of any actual direct encounter with hostile aliens, if he saw a spaceship suddenly appear, he admitted that he'd probably do as Scott suggested and just "run for it."
Black holes and X-rays
Black holes represent one of the deadliest members of the cosmic zoo. Although such beasts were first hypothesized nearly 100 years ago, the result of a detailed analysis of Albert Einstein's Theory of Relativity, evidence for the first suspected black hole didn't come until 1964 when a rocket flight designed to scan for X-ray sources discovered extremely powerful x-rays emanating from the constellation of Cygnus, the Swan. Labeled Cygnus X-1, the first x-ray source in that constellation, it soon became clear that the x-rays come from what was once a massive star 40 times larger than our sun. At the end of the star's life, it collapsed into the black hole.
The X-rays occur because the black hole forms a binary star system with a blue giant star. The black hole slowly cannibalizes its companion, and as the stolen material falls into the black hole, it emits a death cry in the form of powerful x-rays. Cygnus X-1 is the second closest known black hole to Earth. Black holes are invisible. Unless one has a companion to feed it, there would be no evidence of its existence. So if a solitary black hole happens to be moving toward us, we'd never know it until it was too late.
Planet visibility report
As June begins, Mercury and Venus grace the morning pre-dawn sky. Venus is unmistakable, rising two hours before the sun and easily outshining everything in the sky before the sun rises. Jupiter rides high in the south at sunset and Saturn hits the western horizon half an hour after sunset. By the month's end, Venus remains as the brilliant “Morning Star” while Mercury and Mars are lost in the evening twilight. Jupiter remains visible in the post-sunset night sky until 1:30 a.m. and Saturn rises an hour before sunset. Full moon occurs on June 9 with the new moon following on the June 23.
Wayne Harris-Wyrick is an Oklahoma astronomer and former director of the Kirkpatrick Planetarium at Science Museum Oklahoma. Questions or comments may be emailed towizardwayne@zoho.com.
As for an alien race wanting to steal our resources, any civilization advanced enough to come here has likely used all the resources of its own solar system — every planet, moon and asteroid. Such aliens likely have the ability to create what they need from simpler materials in their own backyard, “rather than traveling across the galaxy for a very limited supply,” Shostak said.
