New York, June 26, 2017: Researchers, including one of the Indian-origin, have found evidence of an unknown, Mars-sized “planetary mass object” lurking in the outer reaches of our solar system. This object would be different from — and much closer than — the so-called Planet Nine, a planet whose existence yet awaits confirmation, according to the study to be published in a forthcoming issue of the Astronomical Journal.
In the paper, Kat Volk and Renu Malhotra of the University of Arizona’s Lunar and Planetary Laboratory (LPL) present compelling evidence of a yet-to-be-discovered planetary body with a mass somewhere between that of Mars and Earth. The mysterious mass, the authors showed, has given away its presence — for now — only by controlling the orbital planes of a population of space rocks known as Kuiper Belt Objects (KBO), in the icy outskirts of the solar system.
While most KBOs — debris left over from the formation of the solar system — orbit the Sun with orbital tilts (inclinations) that average out to what planetary scientists call the invariable plane of the solar system, the most distant of the Kuiper Belt’s objects do not. Their average plane, Volk and Malhotra discovered, is tilted away from the invariable plane by about eight degrees. In other words, something unknown is warping the average orbital plane of the outer solar system. “The most likely explanation for our results is that there is some unseen mass,” says Volk, a postdoctoral fellow at LPL and the lead author of the study.
“According to our calculations, something as massive as Mars would be needed to cause the warp that we measured,” Volk said. For the study, Volk and Malhotra analysed the tilt angles of the orbital planes of more than 600 objects in the Kuiper Belt in order to determine the common direction about which these orbital planes all precess. Precession refers to the slow change or “wobble” in the orientation of a rotating object. (IANS)
The journey of NASA’s dauntless Voyager 2 spacecraft through our solar system’s farthest reaches has given scientists new insight into a poorly understood distant frontier: the unexpectedly distinct boundary marking where the sun’s energetic influence ends and interstellar space begins.
The U.S. space agency previously announced that Voyager 2, the second human-made object ever to depart the solar system following its twin Voyager 1, had zipped into interstellar space on Nov. 5, 2018, at a point more than 11 billion miles (17.7 billion km) from the sun. Several research papers published Monday provided scientific details of that crossing.
Both Voyager 1 and Voyager 2 were launched in 1977, designed for five-year missions. Voyager 1 left the solar system at a different location in 2012. Both are now traversing the Milky Way galaxy’s interstellar medium, a chillier region filling the vast expanses between the galaxy’s stars and planetary systems.
The solar wind — the unending flow of charged particles emanating from the outer atmosphere of the sun — creates an immense protective bubble called the heliosphere that envelopes the solar system. The boundary of the solar system — the place where the solar wind ends and interstellar space begins — is called the heliopause.
Voyager 2’s scientific instruments detected abrupt differences in plasma density and magnetic particles upon crossing the heliopause, the researchers said. The researchers said the heliopause appeared to be much thinner than expected.
Plasma — the fourth state of matter after solids, liquids and gases — exists in the solar system as a soup of the charged particles beaming continuously outward from the sun and clashing with interstellar plasma that darts inward from other cosmic events like stellar explosions.
“This is a very exciting time for us,” California Institute of Technology physicist Edward Stone, project manager of the Voyager program, told reporters. “We will see a transition from the magnetic field inside to a different magnetic field outside, and we continue to have surprises compared to what we had expected.”
The electromagnetic junction just outside the heliosphere was thought to be a deeper transitional place of intermingling cosmic weather, but Voyager 2’s plasma wave instrument — built by University of Iowa researchers — detected sharp jumps in plasma density, much like two different fluids coming into contact with one another.
“Think of a cold front that forms when a very cold air mass comes down to the U.S. from Canada,” said Don Gurnett, professor of physics at the University of Iowa. “Here we find a very hot plasma mass coming outward from the sun that encounters the cold plasma in the interstellar medium. It does not surprise me that a sharp boundary forms.”
Scientists are still trying to understand the nature of interstellar space wind and how much of it can seep through the heliopause to reach planets in our solar system.
“We also have galactic cosmic rays, which are out in the interstellar space trying to flow in,” Stone said, referring to the fast-moving, high-energy atomic particles whizzing around the universe. “And some of them, only about 30 percent of what’s outside, can actually reach Earth.”
Voyager 2 entered the interstellar medium far beyond the orbit of Pluto at a spot about 120 times further from the sun than Earth’s orbit.