Astronomy news

Dione

The Cassini spacecraft has detected a thin atmosphere that includes oxygen and ozone on Saturn's moon, Dione - see www.jpl.nasa.gov/news/news.cfm?release=2012-056&cid=release_2012-056. Admittedly, it is a faint atmosphere but enough to get news of it published in Geophysical Research Letters. Oxygen, it seems, is common in the Saturn system, already detected on the moon Rhea and in the rings around the planet.

Fireballs in February

At http://fireballs.ndc.nasa.gov there is information on fireballs over North America - and presumably elsewhere too. The story can also be seen at www.physorg.com/print249203167.html and it seems that in this february just gone there were some rather large space rocks entering the atmosphere of the earth. They were peculiar in that they were slow and penetrated much further and deeper than they are prone to do, breaking up closer to the surface. The origin of them is also somewhat puzzling as they have different orbits and trajectories.

Titan

At www.jpl.nasa.gov/news/news.cfm?release=2012-048&cid=release_2012-048 there is some interesting information available about Saturn's moon, Titan, the subject of a number of papers in the science press recently. The Cassini spacecraft has beamed back some wonderful images and has shown how Titan's atmosphere resembles that of the earth - with clouds, rainfall, and river valleys, lakes and other geological characteristics that have surprised astronomers to a certain degree.

The Earth ... spinning faster?

At www.physorg.com/print248347427.html ... tells us that a NASA JPL research team in league with French scientists have written a paper for the Geophysical Review Letters that claim that for a couple of weeks in 2009 the Earth was spinning faster, and days were shorter - by a fraction of time. This was all because the ocean current that encircles the Antarctic changed rate in response to a down step in wind speed. The change in speed of rotation was a self correcting motion in order to conserve angular momentum.

Venus ... variable day lengths

An unusual story can be found at www.esa.int/export/esaSC/SEM0TLSXXXG_index_0.html (hat tipped towards member Gary Gilligan) from the European Space Agency web site, 10th February 2012. ESAs Venus Express spacecraft has discovered Venus is rotating a little slower than when it was previously measured in the 1990s by NASAs Magellan Orbiter spacecraft. The measurements are said to be precise and detailed and the idea appears to be to find out if Venus has a liquid or a solid core. What might cause it to slow? It has a dense atmosphere which could influence the rotation rate, it is argued.

Black Holes gobbling Asteroids and Comets

This story is at www.sciencedaily.com/releases/2012/02/120208133039.htm and apparently the giant black hole at the centre of our galaxy may be devouring asteroids and comets, or anything that comes within munching reach. This, it is argued, will explain the frequent flares observed by NASAs Chandra x-ray observatory. The paper, published in Monthly Notices of the Royal Astronomical Society, suggests that large numbers of asteroids are needed in order to produce the amount of flaring in the assumed black hole. Why else would the flaring take place?

Richard Mackey and the orbit of the Sun around the barycentre of the solar system

There is surprisingly a lot a sites out there that picked up on Richard Mackey's article in 2007. For instance, at http://climatechange.thinkaboutit.eu/think4/post/climate_change_caused_b... ... it seems Jupiter moves on an eloptic trajectory and one Jovian year = 11.86 Earth years. Is it thus a coincidence that one sunspot cycle of the Sun takes 11 years?

The Moon and the Weather

In the grander picture the galaxy rotates at a roughly constant velocity and relative to this the Sun and its planetary system move around the galactic centre in an elliptical orbit estimated to take around 240 million years - see http://robertkernodle.hubpages.com/hub/The-Cosmology-Climate-Connection-.... The Sun and the solar system have a round and round motion around the galactic centre and an up and down motion across the galactic plane - simultaneously.

The Heartbeat of the Earth

Deep ocean sediment cores, drawn from the Atlantic, Indian and Pacific oceans, are said to show a heartbeat of the Earth's ecosystem, a 100,000 year (100ka) cycle of eccentricity that is modulated and amplified by smaller cycles of recession (23ka) and obliquity (41ka). That is the consensus view - earth's orbit around the sun is elliptical in shape rather than strictly circular. Over time the the shape of the orbit changes from elliptical to less so.

Black Holes and Star formation

There has been a lot of speculation recently on what black holes actually do and the consensus seems to be moving towards the idea the stars may form out of black holes. We begin with an image from the Hubble Space Telescope (see www.physorg.com/print247478317.html ) which shows a filament of ionised gas found near some newly formed stars. The 'unseen' black hole is to the right of the image - but you can't see it.