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Astronomers Locate Oldest Known Solar System

By David Reneke

At 11.2 billion years of age, Kepler-444 is the oldest star with Earth-like planets ever found.

A Sun-like star with orbiting planets, dating back to the dawn of the galaxy, has been discovered by an international team of astronomers. At 11.2 billion years old it is the oldest star with Earth-sized planets ever found, and proves that such planets have formed throughout the history of the universe.

The star, Kepler-444, hosts five planets smaller than Earth, with sizes varying between those of Mercury and Venus. “We’ve never seen anything like this – it is such an old star and the large number of small planets make it very special,” said Dr Daniel Huber from the University of Sydney’s School of Physics. “It is extraordinary that such an ancient system of terrestrial-sized planets formed when the universe was just starting out, at a fifth its current age.”

Kepler-444 is two-and-a-half times older than our solar system, which is only a youthful 4.5 billion years old. “This tells us that planets this size have formed for most of the history of the universe and could provide scope for the existence of ancient life in the galaxy,” Huber said.

The research team used “asteroseismology” to determine the age of the star and planets. This technique measures oscillations of the host star caused by sound waves trapped within it. These lead to miniscule pulses in the star’s brightness, allowing researchers to measure its diameter, mass and age.

The presence and size of the planets are detected by the dimming that occurs when the planets pass across the face of the star. This fading in the intensity of the light received from the star enables scientists to accurately measure the sizes of the planets relative to the size of the star. For the smallest planet in the Kepler-444 system, which is slightly larger than Mercury, the team measured its size with an uncertainty of only 100 km.

Discoveries like this provide important clues about whether a planet that is more truly comparable to Earth may exist – an Earth-sized planet with a 1-year orbit around a star similar to our Sun.

NASA Closes in on Pluto

Pluto’s discoverer, Clyde Tombaugh, could only dream of a spacecraft flying past the small planet he spotted on the edges of the solar system in 1930. Yet the newest views of Pluto streaming in from NASA’s approaching New Horizons probe hint at just how close that dream is to coming true.

Tombaugh died in 1997 but the enigmatic world he discovered in 1930 still remains a mystery. What is it and where did it come from? We simply don’t know, but we will soon!

“These first images of Pluto, clearly brighter and closer than anything ever seen before, represent our first steps at turning the pinpoint of light Clyde saw in the telescopes at Lowell Observatory 85 years ago into a planet before the eyes of the world mid-year,” said New Horizons Principal Investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado.

The new images showing Pluto and its largest moon, Charon, were taken with New Horizons’ telescopic Long Range Reconnaissance Imager (LORRI), representing the first acquired during the spacecraft’s 2015 approach to the Pluto system. It’s all leading to New Horizons’ close flyby of Pluto and its system of moons on 14 July this year.

The dwarf planet will continue to grow larger and larger in the images as the spacecraft hurtles toward its targets. Over the next few months, LORRI will take hundreds of pictures of Pluto against star fields to refine the team’s estimates of New Horizons’ distance to Pluto.

Closing in on Pluto at 14 km/s, New Horizons has already covered more than 4 billion kilometres since it launch on 19 January 2006. Its epic journey has taken it past each planet’s orbit from Mars to Neptune in record time, and it is now in the first stage of an encounter with this world we all grew up with and cried over when it was demoted to dwarf planet status in 2006.

“My dad would be thrilled with New Horizons,” said Annette Tombaugh, Clyde Tombaugh’s daughter. “To actually see the planet that he had discovered and find out more about it, to get to see the moons of Pluto – he would have been astounded. I’m sure it would have meant so much to him if he were still alive today.”

David Reneke is an astronomy lecturer and teacher, a feature writer for major Australian newspapers and magazines, and a science correspondent for ABC and commercial radio. Subscribe to David’s free Astro-Space newsletter at www.davidreneke.com