Archive for the ‘Milky Way galaxy’ Category

Artist's impression of planets discovered by Kepler spacecraft

Our galaxy probably contains at least two billion planets that, like Earth, have liquid water on their surfaces and orbit around their parent stars in the “habitable zone” for life. The nearest, according to astronomers, could be a mere 12 light years away.

A new study, published on Monday in the Proceedings of the National Academy of Sciences, suggests that Earth-like planets capable of supporting life are far more common than previously thought. Using measurements from Nasa’s Kepler space observatory, scientists led by Erik Petigura at the University of California, Berkeley, estimated that 22% of our galaxy’s sun-like stars have rocky planets circling them in the zone where they get roughly the same amount of light energy as Earth receives from the sun. There are around 100bn stars in our galaxy, of which 10% are like the sun.

So far Kepler has studied more than 150,000 stars and identified more than 3,000 candidate planets, but many of these are “gas giants”, similar to Jupiter, that orbit close to their parent stars. If there is life out there, it is far more likely to have evolved on rocky planets with liquid water on their surfaces, similar to Earth.

To get their results, Petigura’s team looked for planets in Kepler data that had a radius up to double that of Earth. They searched for planets that orbited far enough from their star that liquid water would not evaporate, but not so far that the water would all freeze.

Subhanjoy Mohanty, an astrophysicist at Imperial College London who was not involved with the study, said: “This is the first estimate of the frequency of Earth-like planets around sun-like stars, in orbits large enough to lie in the habitable zone of their stars. The finding that roughly one in five sun-like stars may host such planets is an incredibly important one, probably exceeding the expectations of most cautious astronomers.”

He added that the latest analysis increased the chances that there might be life somewhere among the stars. “Previous analyses of Kepler data had shown that red dwarfs – the most common type of star in the galaxy, making up about 80% of the stellar population – very frequently harbour Earth-size planets, including in their habitable zones. This new study shows that the same is true around stars more like our own sun. This is certainly an added impetus for planned future missions which will study the atmospheres of these potentially habitable planets, enabling us to investigate whether they are in fact habitable or not, and also whether their atmospheres show actual biosignatures of existing life.”

Nasa also announced on Monday that the Kepler probe would be given a new lease of life, following fears that it would have to end its mission after only four years in space. In May 2013, scientists discovered that one of the gyroscopic wheels – known as “reaction wheels” – that kept the probe pointing in the right direction had stopped working and, try as they might, Nasa engineers could not restart it. Unable to point itself at the stars with any accuracy, the probe could no longer be used to collect data about the position of new exoplanets.

But it looks as though there could be a solution that involves reorienting the probe to look along the plane of the galaxy, which will allow it to remain stable with only two of its reaction wheels working. “The old saying ‘necessity is the mother of invention’ has rung true here, with engineers and scientists from Nasa and the spacecraft manufacturers having figured out this way to – we hope – recover much of the performance we thought we had lost. We are very excited,” said Bill Chaplin, an astrophysicist at the University of Birmingham in the UK.

If all goes well, the new Kepler mission – dubbed “K2” – will look for planets around smaller stars than the sun, and will also study the stars themselves. “There are a wealth of fantastically interesting targets for astrophysics that can be observed in the ecliptic plane, which were not accessible in the original Kepler field, notably brighter clusters of stars – where the common origins and distances to these stars make the clusters excellent laboratories for testing our understanding of stars – and young, star-forming regions,” said Chaplin.

http://www.theguardian.com/science/2013/nov/04/planets-galaxy-life-kepler

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

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The dung beetle is now the first animal proven to use the light of the milky way for orientation and navigation, thanks to new research from Wits University. The vast and dim milky glow of our home galaxy apparently provides a good source of orientation when the Sun or a bright Moon isn’t available.

Dung beetles don’t have eyes thaf are sharp enough to clearly distinguish between exact constellations (from our current understanding of their eyes. They rely on the overall gradient of light to dark, that the light of the Milky Way provides, to get a sense of orientation. This allows them to make sure that when they are harvesting dung from a dung pile, that they continue moving away from it instead of accidently circling back into their competitors.

“The dung beetles don’t care which direction they’re going in; they just need to get away from the bun fight at the poo pile,” claims Professor Marcus Byrne from Wits University.

The researchers have previously published other findings on the dung beetle, including proving that dung beetles make use of the Sun, the Moon and polarised light for orientation and navigation.

For the first experiments, the dung beetles had their eyes covered up and blocked with “caps”, and were then observed. During the research, a seemingly new behavior was also discovered. The dung beetles were observed climbing to the top of their dung balls, and then using the higher position to locate the sources of light that they then used for orientation, the researchers labelled it as a “dance”.

To follow up on that first research, further experiments were then conducted under the simulated light and night sky of the Wits Planetarium. In the planetarium, the beetles were very clearly shown to be using the Mohawk of the Milky Way for orientation and navigation.

“We were sitting out in Vryburg (conducting experiments) and the Milky Way was this massive light source. We thought they have to be able to use this — they just have to!” said Byrne.

“Not all light sources are equally useful landmarks for a dung beetle. A moth keeping a constant angle between itself and a candle flame will move in a circle around the flame. However, a celestial body is too far away to change position relative to a dung beetle as it rolls its ball, with the result that the beetle keeps travelling in a straight line.”

It’s very likely that the dung beetles have some ‘hierarchy of preference’ as far as available light sources goes, but it’s not entirely clear yet what it is. If both a bright moon and the Milky Way were both visible, it’s assumed that the beetles would focus on one.

There have actually been quite a few animals that have been proven to make use of the stars as a way to orient themselves and navigate the world. The dung beetle is, for now, the only animal shown to use the Milky Way for this purpose.

Many species of birds have been found to make use of star light as a navigation tool (in addition to magnetoreception, smell, and vision), as well as species of insects, and very likely other animals also. There has been some research in recent years suggesting that as light pollution from human settlements has been increasing many species have been losing their ability to navigate properly, especially during important times such as when some species gather for mating. Anyone who has ever witnessed a large swarm or gathering around an artificial light source can attest to this.

Here’s some more information on the Milky Way, and observing it in the night’s sky:

“The Milky Way is the galaxy that contains our Solar System. This name derives from its appearance as a dim ‘milky’ glowing band arching across the night sky, in which the naked eye cannot distinguish individual stars. The term ‘Milky Way’ is a translation of the Classical Latin via lactea, from the Hellenistic Greek γαλαξίας κύκλος (pr. galaxías kýklos, ‘milky circle’). The Milky Way appears like a band because it is a disk-shaped structure being viewed from inside. The fact that this faint band of light is made up of stars was proven in 1610 when Galileo Galilei used his telescope to resolve it into individual stars. In the 1920s, observations by astronomer Edwin Hubble showed that the Milky Way is just one of many galaxies.”

“When observing the night sky, the term ‘Milky Way’ is limited to the hazy band of white light some 30 degrees wide arcing across the sky (although all of the stars that can be seen with the naked eye are part of the Milky Way Galaxy). The light in this band originates from un-resolved stars and other material that lie within the Galactic plane. Dark regions within the band, such as the Great Rift and the Coalsack, correspond to areas where light from distant stars is blocked by interstellar dust.”

“The Milky Way has a relatively low surface brightness. Its visibility can be greatly reduced by background light such as light pollution or stray light from the moon. It is readily visible when the limiting magnitude is +5.1 or better, while showing a great deal of detail at +6.1. This makes the Milky Way difficult to see from any brightly lit urban or suburban location but very prominent when viewed from a rural area when the moon is below the horizon.”

“The Galactic plane is inclined by about 60 degrees to the ecliptic (the plane of the Earth’s orbit). Relative to the celestial equator, it passes as far north as the constellation of Cassiopeia and as far south as the constellation of Crux, indicating the high inclination of Earth’s equatorial plane and the plane of the ecliptic relative to the Galactic plane. The north Galactic pole is situated at right ascension 12h 49m, declination +27.4° (B1950) near beta Comae Berenices, and the south Galactic pole is near alpha Sculptoris. Because of this high inclination, depending on the time of night and the year, the arc of Milky Way can appear relatively low or relatively high in the sky. For observers from about 65 degrees north to 65 degrees south on the Earth’s surface the Milky Way passes directly overhead twice a day.”

Read more at http://planetsave.com/2013/01/26/dung-beetle-uses-the-milky-way-for-navigation-first-animal-found-to-do-so/#wkpSTvZ3yUmblrMW.99
Planetsave (http://s.tt/1yZ5b)

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An international team of astronomers led by the University of Hertfordshire has discovered that Tau Ceti, one of the closest and most Sun-like stars, may host five planets — with one in the star’s habitable zone.

At a distance of twelve light years and visible with the naked eye in the evening sky, Tau Ceti is the closest single star that has the same spectral classification as our Sun. Its five planets are estimated to have masses between two and six times the mass of Earth — making it the lowest-mass planetary system yet detected. One of the planets lies in the habitable zone of the star and has a mass around five times that of Earth, making it the smallest planet found to be orbiting in the habitable zone of any Sun-like star.

The international team of astronomers, from the UK, Chile, the USA, and Australia, combined more than six-thousand observations from three different instruments and intensively modelled the data. Using new techniques, the team has found a method to detect signals half the size previously thought possible. This greatly improves the sensitivity of searches for small planets and suggests that Tau Ceti is not a lone star but has a planetary system.

Mikko Tuomi, from the University of Hertfordshire and the first author of the paper, said: “We pioneered new data modelling techniques by adding artificial signals to the data and testing our recovery of the signals with a variety of different approaches. This significantly improved our noise modelling techniques and increased our ability to find low mass planets.”

“We chose Tau Ceti for this noise modelling study because we had thought it contained no signals. And as it is so bright and similar to our Sun it is an ideal benchmark system to test out our methods for the detection of small planets,” commented Hugh Jones from the University of Hertfordshire.

James Jenkins, Universidad de Chile and Visiting Fellow at the University of Hertfordshire, explained: “Tau Ceti is one of our nearest cosmic neighbours and so bright that we may be able to study the atmospheres of these planets in the not too distant future. Planetary systems found around nearby stars close to our Sun indicate that these systems are common in our Milky Way galaxy.”

Over 800 planets have been discovered orbiting other worlds, but planets in orbit around the nearest Sun-like stars are particularly valuable. Steve Vogt from University of California Santa Cruz said: “This discovery is in keeping with our emerging view that virtually every star has planets, and that the galaxy must have many such potentially habitable Earth-sized planets. They are everywhere, even right next door! We are now beginning to understand that Nature seems to overwhelmingly prefer systems that have a multiple planets with orbits of less than one hundred days. This is quite unlike our own solar system where there is nothing with an orbit inside that of Mercury. So our solar system is, in some sense, a bit of a freak and not the most typical kind of system that Nature cooks up.”

“As we stare the night sky, it is worth contemplating that there may well be more planets out there than there are stars … some fraction of which may well be habitable,” remarked Chris Tinney from the University of New South Wales.

Journal Reference:

1.M. Tuomi, H. R. A. Jones, J. S. Jenkins, C. G. Tinney, R. P. Butler, S. S. Vogt, J. R. Barnes, R. A. Wittenmyer, S. O’Toole, J. Horner, J. Bailey, B. D. Carter, D. J. Wright, G. S. Salter, D. Pinfield. Signals embedded in the radial velocity noise. Periodic variations in the tau Ceti velocities. Astronomy & Astrophysics, 2012; DOI: 10.1051/0004-6361/201220509

http://www.sciencedaily.com/releases/2012/12/121219084102.htm