Space :: TechMediaNetwork :: February 12, 2012 :: :: Email :: Print Subdued seasonality might be linked to the emergence of complex life on Earth around 600 million years ago By Adam Hadhazy and SPACE.com
IS IT possible to tell whether a planet hosts life just from its glow? A new analysis of Earthshine , sunlight reflected off Earth then bounced back by the moon, suggests this is a viable way to seek life on exoplanets. Life co-exists with certain chemicals that leave their imprint on the light Earth reflects, while plants reflect light differently to rocks.
The Solar System & Milky Way
What is Reality
In honor of the Nobel Prize , here are some questions that are frequently asked about dark energy, or should be.
Sometimes nature just throws you a loop. All your carefully laid plans, all your exquisite calculations, all your deeply held beliefs and expectations get blown away in the simple eloquence of real data from the real world . That is how Dark Energy made its appearance into the world of cosmology. Its not just that folks weren't expecting it. They were, in fact, expecting the very opposite. Last week I explained how Dark Matter was "discovered" (inferred really), based on observations over decades of the gravitational influence it exerts on matter we can see (the stuff we are made of).
The universe's oldest light and its largest objects could provide a new way to study dark energy, the mysterious entity believed to be pushing the universe apart at an ever-faster rate. The discovery of the universe's accelerating expansion earned three physicists a Nobel prize last year, but no one knows its source. "What's causing the acceleration?" asks Rachel Bean of Cornell University in Ithaca, New York.
Dark matter is slowly running out of places to hide. Two new looks at the gamma-ray sky suggest that if the mysterious matter is a particle, it is heavier than 40 gigaelectronvolts, about 44 times the mass of a proton. That contradicts hints from three experiments on Earth that pointed to a lightweight dark matter particle weighing just a quarter as much, although some researchers say such featherweights are still in the running. Dark matter makes up about 80 per cent of the matter in the universe, but no one is sure what it's made of. The leading candidate is a WIMP, or weakly-interacting massive particle, that was produced in the big bang and has been clumping up and seeding structures such as galaxies ever since.
We may not know what dark matter is, but we can still put it to work. The largest map of dark matter ever made (pictured) is one of several new ones that will help to nail the properties of the equally mysterious dark energy , which is thought to drive the universe's accelerating expansion. A group led by Catherine Heymans of the University of Edinburgh, UK, and Ludo Van Waerbeke of the University of British Columbia, Vancouver, Canada, presented the huge map at the American Astronomical Society (AAS) meeting in Austin, Texas, this week. Dark matter makes up 83 per cent of the universe's matter, but is invisible, so its presence must be inferred from its gravitational influence. This works because clumps of dark matter distort the space-time around them. Light from distant galaxies passing through those regions also gets warped, making the galaxies appear streaked and smeared in telescope images, a technique known as weak gravitational lensing.
Read full article Continue reading page | 1 | 2 | 3 Far from shedding light on dark matter, our first experimental glimpses of the elusive stuff have only deepened its mystique
Two years ago several of my Sci Am colleagues and I had an intense email exchange over a period of weeks, trying to figure out what to make of a new paper by string theorist Erik Verlinde . I don’t think I’ve ever been so flummoxed by physicists’ reactions to a paper. Mathematically it could hardly have been simpler—the level of middle-school algebra for the most part. Logically and physically, it was a head-hurter.
Want to stay on top of all the space news? Follow @universetoday on Twitter Astronomers using NASA’s Fermi Gamma-Ray Space Telescope have been looking for evidence of suspected types of dark matter particles within faint dwarf galaxies near the Milky Way — relatively “boring” galaxies that have little activity but are known to contain large amounts of dark matter.
Space :: TechMediaNetwork :: January 10, 2012 :: :: Email :: Print Scientists hope that by plotting out the distribution of dark matter throughout space, they will come closer to understanding what it is By Clara Moskowitz and SPACE.com This giant map of invisible dark matter recorded in four directions by the Canada-France-Hawaii Telescope during each season of the year was released on January 9, 2012. The color inset shows the previous largest COSMOS dark matter map and the size of the full moon (as it would appear to the telescope) to scale. Image: Van Waerbeke, Heymans, and CFHTLens collaboration.
New calculations suggest dearth of invisible substance in solar neighborhood By Nadia Drake Web edition: April 20, 2012 Print edition: May 19, 2012; Vol.181 #10 (p. 5) Enlarge
Want to stay on top of all the space news? Follow @universetoday on Twitter Arp 302 consists of a pair of very gas-rich spiral galaxies in their early stages of interaction.
A galaxy cluster with the distribution of dark matter marked by purple overlay. Credit: NASA, ESA, E. Julio (JPL/LAM), P. Natarajan (Yale) and J-P.
THE skeleton of dark matter that undergirds the cosmic web of matter in the universe has been clearly detected for first time. We know that matter in the cosmos forms a web, with galaxies and clusters linked by filaments across mostly empty space. Filaments are made of normal matter and dark matter - the unseen stuff that makes up about 85 per cent of the universe's mass. Recent observations have seen the normal matter in such filaments .