Wednesday, June 26, 2013
So what's the book about? It's a police procedural, anti-fantasy story where a dead body is found in one city, but the murder appears to have taken in another city. However, while these two cities are in exactly the same place, they are in completely separate countries and people from one cannot see, hear, or interact with those of the other. As the investigation proceeds, we learn both rumors and facts about that which lurks in the gaps between the city and the city.
Read on for my (spoiler-free) review.
Tuesday, June 25, 2013
|Artistic depiction of the view from Gliese 667Cd. Credit: ESO/M. Kornmesser|
The recent news is that 2 more planets in the Habitable Zone of the star Gliese 667 (aka GJ667) have just been discovered. These are GJ667C f and e. I had previously written about GJ667Cc, another habitable world in the same system. It appears that this star system could host 3 planets that, if the conditions are right, could harbor liquid water on the surface of the planet.
These planets join a growing list of potentially habitable planets.
|List of potentially habitable planets. Credit: PHL @ UPR Arecibo|
The figure above shows a dozen planets thought to be most likely to be habitable. Note that a few, like Gliese 581g, are unconfirmed.
The planets are ranked by the "Earth Similarity Index" or ESI, which I recently learned is an index that measures how similar a planet is to the Earth. It compares the radius, density, surface temperature, and escape velocity to that of Earth's and values close to 1 are very good (ie, Earth-like). I was surprised to see escape velocity among the parameters (since it depends on the mass and radius) given that the density, which also folds in the mass and radius, is already considered.
Note that despite the high temperature on the surface of Venus, the mass and radius are so similar to the Earth that the ESI is close to 0.8. However, Venus is not in the habitable zone as it's too close to the Sun.
This is an exciting time for planetary research in astronomy as more and more planets are being discovered and we are starting to probe planets whose conditions may be favorable for liquid water and ultimately, we hope, for life.
Friday, June 14, 2013
|Cosmic flow near the Local Group of galaxies. Credit: Courtois et al 2013; Cosmic Flows conference.|
You don't need to be an extragalactic astronomer to find the video below amazing.
This 17-minute video walks you through the distribution and velocities of galaxies within 300 million light-years of the Milky Way Galaxy. Distinct regions like the Virgo Cluster, the Local Void, and the Great Wall are easily seen and pointed out by the video. There's a lot of rotations going on, and the field of galaxies is complex, but the video does a good job of highlighting what's important at each step so that one is not completely overwhelmed. It's great to see where all these structures are and be reminded of how large the Universe is, as I tend to deal with stars that are a million times closer.
Check it out: