ASTRONOMY

To a casual observer it could be the psychedelic creation of a mischievous puppy that has dipped its paws in paint. But it may be one of the most extraordinary pictures ever snapped.

It is, scientists said yesterday, the glow from the first things to form in the universe, more than 13 billion years ago. Snapped by NASA's Spitzer space telescope, the bizarre objects must have existed within a few hundred million years of the Big Bang, 13.7 billion years ago.

An Australian astrophysicist, Ray Norris, said the NASA team may have found "the holy grail" of astronomy.

What the ancient objects are remains a mystery. One possibility is stars, the first to light up after the dawn of time. They would have been "humungous", said NASA, "more than 1000 times the mass of our sun". Or they may be "voracious black holes". While black holes are invisible, heat emitted by matter plunging into them can be detected.

"Whatever these objects are," said Alexander Kashlinsky, of NASA's Goddard Space Flight Centre, "they are intrinsically incredibly bright and very different from anything in existence today." The image was made by Spitzer shooting pictures of five areas of the sky. All light from stars and galaxies in the foreground was then removed, leaving only the ancient infrared glow.

"Imagine trying to see fireworks at night from across a crowded city," Dr Kashlinsky said. "If you could turn off the city lights, you might get a glimpse at the fireworks. We have shut down the lights of the universe to see the outlines of its first fireworks."

Professor Norris, from the CSIRO's Australia Telescope, said the image did not show the objects themselves, but their glow that was radiating from all parts of the sky, because "the early universe is all around us." The next step would be to find and get direct images of the objects. "Many of us are searching for these objects," he said.

He believed locating them would be possible with the James Webb space telescope, the Hubble's successor, to be launched in the next decade, and the Square Kilometre Array, a radio telescope that may be built in Australia. Professor Norris conceded astronomers could not explain how such big objects formed so quickly after the Big Bang.

A newfound planet has three suns, a scientist says—a discovery that highlights the unimagined beauties the cosmos still has in store for us, suggests planets are even more common than previously believed, and could rewrite theories of planet formation.

Since the planet is thought to be a gaseous giant, it would probably be impossible in practical terms to view the sunset from there. Therefore, the artist envisioned the sunset as viewed from a hypothetical moon of that planet. The large yellow sun is already halfway over the horizon. The planet also appears in the upper left.

The California Institute of Technology researcher reported finding the planet in the direction of the constellation Cygnus (The Swan), in a paper published in the July 14 issue of the research journal Nature. The planet is slightly larger than Jupiter, the author said, and the fact that it’s being pulled in three different directions by the gravity of nearby stars makes it hard to see how it survives.

The finding promises to “seriously challenge our current understanding of how planets are formed,” according to an emailed statement from the institute. The finding could shed light on the possibility that planets can exist in multiple star systems—groups of two, three or more stars that orbit each other due to their mutual gravity.

In the paper, Maciej Konacki, a senior postdoctoral scholar at the institute, said the newfound world orbits one star of a triple-star system known as HD 188753. It doesn’t orbit the other two, so these aren’t its “suns” in the traditional sense of being stars around which it orbits. But they do circle around the same, main star that the planet orbits. The three stars are about 149 light-years from Earth, Konacki said. A light-year is the distance light travels in a year. The stars are about as close to one another as the distance between our sun and Saturn, he added.

A viewer on the planet would see three bright “suns,” according to Konacki. One of these three suns, the one that the planet orbits, would look huge, he added. This is because the planet is extremely close to that star, and therefore orbits it quickly: its year is only 3½ days long. That star would also be yellow, being similar to our own sun. The larger of the other two suns would be orange, and the smaller red, Konacki said.

Konacki calls the new type of planet a “Tatooine planet,” because of a similarity to Luke Skywalker’s view of his home planet’s sky in Star Wars. That planet, however, had a mere two suns.

“The environment in which this planet exists is quite spectacular,” said Konacki. “With three suns, the sky view must be out of this world—literally and figuratively.”

The fact that a planet can even exist in a multiple-star system is amazing, he added. Double-, triple- and multiple stars are quite common in our corner of the galaxy, and in fact these systems outnumber single stars by some 20 percent. Researchers have found most of the planets discovered so far outside our solar system by carefully measuring the speed of the stars, a technique that is simpler with single stars.

Experts generally avoided planet-hunting in multiple-star systems where the stars are close to each other, as in this case, Konacki explained. This is because existing planet detection techniques fail for such complicated systems, and most solar-system formation theories suggest planets are unlikely to form in such environments.

Konacki said he made his discovery by developing a new method that lets him precisely measure velocities of all stars in such systems. He used the technique to hunt for planets in such systems with the Keck I telescope in Hawaii. The planet in the HD 188753 system is the first one from this survey, he said.

“Planets from complicated stellar systems will put our theories of planet formation to a strict test,” Konacki remarked. “If we believe that the same basic processes lead to the formation of planets around single stars and components of multiple stellar systems, then such processes should be equally feasible, regardless of the presence of stellar companions.”

Scientists in 1995 discovered the first “hot Jupiter,” a planet outside our Solar System that is a giant, like Jupiter, and that orbits very close to its parent star. Today, more than 20 such planets are known to orbit other stars. Such planets are believed to form in a disk of gas and dust that extends beyond three astronomical units, or three times the 93-million-mile distance between the sun and Earth. After formation, the planets are thought to migrate inward to their present close orbits.