Spectacular Venus-Jupiter conjunction on 30 June

Tonight – June 30, 2015 – and tomorrow night, look for the sky’s brightest and second-brightest planets to stage their closest conjunction until August, 2016. Venus and Jupiter will be less than one-half degree apart. That’s less than the moon’s diameter on our sky’s dome

venus-jupiter-6-30-2015-Melaka-Malaysia-Mohamad-Fadzli.

Venus is currently about to pass between the sun and Earth. It will sweep some 8 degrees S. of the sun on August 15. Meanwhile, Earth passed between Jupiter and the sun in February, 2015. So Jupiter and Venus are nowhere near each other in space.

And yet, as we look outward from Earth, we see these two planets aligned on nearly the same line of sight.

 

Methane in Mars Meteorite Suggests Possibility of Life

Methane, a potential sign of primitive life, has been found in meteorites from Mars, adding weight to the idea that life could live off methane on the Red Planet, researchers say.

This discovery is not evidence that life exists, or has ever existed, on Mars, the researchers cautioned. Still, methane “is an ingredient that could potentially support microbial activity in the Red Planet,” study lead author Nigel Blamey, a geochemist at Brock University in St. Catharines, Ontario, Canada, told Space.com.

Methane is the simplest organic molecule. This colorless, odorless, flammable gas was first discovered in the Martian atmosphere by the European Space Agency’s Mars Express spacecraft in 2003, and NASA’s Curiosity rover discovered a fleeting spike of methane at its landing site last year. [The Search for Life on Mars: A Photo Timeline]

Much of the methane in Earth’s atmosphere is produced by life, such as cattle digesting food. However, there are ways to produce methane without life, such as volcanic activity.

To shed light on the nature of the methane on Mars, Blamey and his colleagues analyzed rocks blasted off Mars by cosmic impacts that subsequently crash-landed on Earth as meteorites. About 220 pounds (100 kilograms) of Martian meteorites have been found on Earth.

The scientists focused on six meteorites from Mars that serve as examples of volcanic rocks there, collecting samples about one-quarter of a gram from each — a little bigger than a 1-carat diamond. All the samples were taken from the interiors of the meteorites, to avoid terrestrial contamination.

The researchers found that all six released methane and other gases when crushed, probably from small pockets inside.

“The biggest surprise was how large the methane signals were,” Blamey said.meteorites-from-mars

Chemical reactions between volcanic rocks on Mars and the Martian environment could release methane. Although the dry thin air of Mars makes its surface hostile to life, the researchers suggest the Red Planet is probably more habitable under its surface. They noted that if methane is available underground on Mars, microbes could live off it, just as some bacteria do in extreme environments on Earth.

“We have not found life, but we have found methane that could potentially support microbes in the subsurface,” Blamey said.

Blamey now hopes to analyze more Martian meteorites. He and his colleagues detailed their findings online today (June 16) in the journal Nature Communications.

Credits: Space.com

 

 

Is Universe really Accelerating?

Said by Brian Koberlein

Recently I’ve been asked about reports of new research showing the universe isn’t accelerating. If true, it would mean that dark energy doesn’t exist, which would be a good way to solve the mystery. While there is the occasional headline making such a claim, there isn’t a great deal of evidence to support the idea. There is, however, plenty of evidence that dark energy exists.

The most recent paper claiming to eliminate (or at least weaken) dark energy showed up recently on the arxiv. It focuses on one keystone of dark energy evidence, the observations of distant supernovae. One particular type of supernova known as Type Ia has the useful property of exploding with a fairly uniform brightness. This means they can be used as “standard candles” to determine their distance. Basically you can observe its apparent brightness and compare it to its actual brightness to get a distance. Observation of some of the most distant supernovae at the time led to the Nobel-winning discovery of dark energy.

But recently there’s been evidence that there is more variation within Type Ia supernovae than originally thought, including a dimmer variation known as Type Iax. This means the uncertainty in the actual brightness of Type Ia supernovae might be greater than we’ve been using, which is where this new paper comes in. Basically what the authors do is analyze the observations we have of distant supernovae using larger uncertainties. They then compare this data to both the accelerating and non-accelerating cosmological models. What they find is that the confidence level of the accelerating model is lowered, which is exactly what you would expect if you make your uncertainties larger. They also find that support for no acceleration increases, which is also what you’d expect with larger uncertainties.

Their conclusion is that the non-accelerating model is “still in the game” as it were, since larger uncertainties make the distinction between the two models less clear. But the evidence doesn’t support that conclusion. The strongest candidate by far is still an accelerating universe based upon this data, and dark energy is supported by other evidence such as galactic clustering and the cosmic microwave background.

In light of new supernova observations, it’s good to keep testing our cosmological models, but so far the standard LCDM model of an accelerating universe is the best model we have

Bottom line: Authors of a recent study published online at arxiv.org analyze observations of distant supernovae using larger uncertainties. They then compare this data to both the accelerating and non-accelerating cosmological models to find that confidence in the accelerating model is lowered. However, that is what you’d expect if you make the uncertainties larger. So far, the standard LCDM model of an accelerating universe still stands.


 

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Brian Koberlein is an astrophysicist and physics professor at Rochester Institute of Technology. In addition to appearing at EarthSky, he also provides clear and current explanations of new discoveries in astronomy and astrophysics at his blog “One Universe at a Time,” as well as on Google+. You can follow him on Twitter @BrianKoberlein

How Bright is Daytime on Pluto?

Lights in the Dark

Concept of Pluto's surface. © Ron Miller, used with permission.Concept of Pluto’s surface. © Ron Miller, used with permission.

We all know that Pluto is very far from the Sun, on average about 40 times as far away from it as Earth is, and as such it is very cold and dark. But just how dark is it on Pluto? If you were an astronaut walking around on Pluto would the Sun really just look like another bright point in an already star-filled sky, or would you actually be able to see the Plutonian landscape around you during the day (like in the illustration above by Ron Miller?)

Actually it’s brighter than you might think, even three and a half billion miles from the Sun. And with the New Horizons spacecraft closing in on the first-ever pass by Pluto in July, NASA has a way for you to get an idea of the type of lighting you would experience on the surface…

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