blog-gasy Siansa: February 2013

Tuesday, February 26, 2013

Russia meteor's origin tracked down

Using amateur video footage, they were able to plot the meteor's trajectory through Earth's atmosphere and then reconstruct its orbit around the Sun.

As the space rock burned up over the city of Chelyabinsk, the shockwave blew out windows and rocked buildings.

The team, from Colombia, has published details on the Arxiv website.

Numerous videos of the fireball were taken with camera phones, CCTV and car-dashboard cameras and subsequently shared widely on the web. Furthermore, traffic camera footage of the fireball had precise time and date stamps.

Early estimates of the meteor's mass put it at ten tonnes; US space agency Nasa later estimated it to be between 7,000 and 10,000 tonnes. Nasa estimates the size of the object was about 17m (55ft).

Using the footage and the location of an impact into Lake Chebarkul, Jorge Zuluaga and Ignacio Ferrin, from the University of Antioquia in Medellin were able to use simple trigonometry to calculate the height, speed and position of the rock as it fell to Earth.

To reconstruct the meteor's original orbit around the Sun, they used six different properties of its trajectory through Earth's atmosphere. Most of these are related to the point at which the meteor becomes bright enough to cast a noticeable shadow in the videos.

The Chelyabinsk meteor (labelled ChM) appears to have been on elliptical orbit around the Sun before it collided with Earth

The researchers then plugged their figures into astronomy software developed by the US Naval Observatory.

The results suggest the meteor belongs to a well known family of space rocks - known as the Apollo asteroids - that cross Earth's orbit.

The BBC's Daniel Sandford says people described a ball of fire in the sky

Of about 9,700 near-Earth asteroids discovered so far, about 5,200 are thought to be Apollos. Asteroids are divided into different groups such as Apollo, Aten, or Amor, based on the type of orbit they have.

Dr Stephen Lowry, from the University of Kent, said the team had done well to publish so quickly.

"It certainly looks like it was a member of the Apollo class of asteroids," he told BBC News.

"Its elliptical, low inclination orbit, indicates a solar system origin, most likely from the asteroid belt between Mars and Jupiter.

Dr Lowry added: "Perhaps with more data, we can determine roughly where in the asteroid belt it come from."

Paul.Rincon-INTERNET@bbc.co.uk

Astronomers have traced the origin of a meteor that injured about 1,000 people after breaking up over central Russia earlier this month.

By Paul Rincon Science editor, BBC News website

Russia meteor's origin tracked down

Thursday, February 07, 2013

LibreOffice, a Free Alternative to Office, Is New and Improved

I understand that some people need Microsoft Office – that for the sake of compatibility, familiarity and features, nothing else will do.

But anyone who doesn’t feel that way should consider trying LibreOffice, a free, open-source alternative. The new version, LibreOffice 4, offers better compatibility and more features than the previous version, along with lots of under the hood improvements.

I’ve been a happy LibreOffice 3 user for about a year, and I wouldn’t say the new version is a drastic change — at least not on its face. Perhaps the most significant new feature is the ability to attach comments to a range of text, not just a single point, which will help improve compatibility with Office documents.

But the lack of flashy changes is okay, I think. While Microsoft seems to make a point of shaking up the look and feel of each new version of its Office suite, part of LibreOffice’s allure is how it stays the same. (In fact, if you hated the Ribbon layout of Office 2007 and beyond, I’d argue that LibreOffice is just the respite you’re looking for.)

Like I said, not everyone will be able to work with LibreOffice. But in my experience it handles basic compatibility very well. It supports all Office file formats, has all the major features you might expect, and gets the job done for typical document and spreadsheet editing. Give it a shot if your office software needs don’t justify Microsoft’s $140-and-up asking price.