Astronomy news

Mars, and Mars

Several posts on Mars today - and the focussed search for water and moisture on the red planet. At ... we have images of dark markings on a Martian slope that changes with the seasons. Scientists have suggested it might indicate salty water that advances seasonally down the slopes. The markings are however somewhat close to the equator - and the terrain is generally arid.

Dead, defunct, abandoned ... Comet ISON

Disappointment all round. Comet ISON is effectively dead - zilch (see There is no evidence of a zombie half existence - or a resurrection along the lines of a flare up after a period of quietude. However, we are informed in this piece that scientists now recognise not all comets are dirty snowballs - some of them are rocky asteroids disguised as comets (such as Comet Wild2). This leaves a problem and this is how can a comet from the outer solar system contain minerals formed in the inner solar system.

Black Holes ... as they are being observed

At ... measurement of polarised light in the afterglow indicates the presence of a stable magnetic field associated with a young black hole - or, deleting the last few words, observation of an area of the sky where gamma ray bursts are being emitted. These are luminous explosions, we are assured - but might they be flares.

What is left of Comet ISON

This story is at ... scientists are still unsure how much of the comet may have survived its encounter with the Sun - if anything but a lot of dust. mOst astronomers believe it was destroyed - 90 per cent is bandied around (but who believes such figure hugging). They think that small pieces of rubble could have survived, up to 1m across. However, it is still possible that larger pieces are still out there moving along the comet's trajectory but these have yet to be observed - and lots of telescopes are still pointed in the direction of ISON.

A Venus space mission?

SIS member William Thompson emails to say Robin Canup, a space scientist with the Southwest Research Institute in Colorado has published a piece in the journal Nature proposing a mission to Venus that he considered would help understand the development of our Moon. She suggests the current theories on how the Moon came about seem to rely too much on data from Mars, and that might obscure the real story of the Moon. Tom Elliot and Sarah Stewart offer their own opinion on the matter - in the News and Views in the same issue of the journal.

The Sun, Van Allen belts, and plasma in Saturn's magnetosphere

At ... NASA solar scientist David Hathaway has published a new paper (see Dec 6th issue of Science journal) which says long lived convection cells have been found on the Sun. Massive, long lasting plasma flows transport heat from the depths of the Sun to the surface - which suggests an old explanation for why the Sun rotates fastest at its equator. There is a video at the link.

Odd Alignments

Peter Knight, in The Cerne Giant - Landscape, Gods, and the Stargate (2012) has made some interesting observations on the Cerne Giant, a Dorset hill figure cut out of the chalk. Variousl theories on its age have been aired over the years, most recently by Darvill (1999), Castleden (1996) and Newman (1997). At one time it was thought the hill figure was cut fairly recently - as a prank.

An electromagnetic shower

The last post was about stellar wind directing material to or from a black hole but what is the connection between the two - one emitting a sort of solar wind and the other throwing out X-rays. The latest post by Tim Cullen just happens to have a bearing - go to ... as he turns his attention to mainstream treatment of cosmic rays - and electromagnetic radiation from space. The post is reblogged at Tall Bloke's Talk Shop and brought to a wider audience, with a knowledgeable group of commenters.

Black Hole Eating Habits

This story is at various places, and for example at ... and black holes are associated with X-ray emissions - but one of them is not playing ball by conforming to the normal eating habits of his compatriot black holes. In fact, they are eating lots of materia very quickly, gobbling it up as a result of being fed lots of dust and gases from a nearby galaxy. However, to the surprise of astrophysicists, the black hole is really quite a small affair, a bit of a runt - in spote of the copious menu.

Phaethon's Tail

At ... the December Geminids are a regular meteor shower emerging out of that part of the sky defined as the constellation of Gemini, and they always appear, year on year. However, their progenitor comet is unknown. There is no comet that matches their orbit - but there is an asteroid. This is Phaethon. It was discovered in 1983 by NASAs IRAS satellite. The problem is that Phaethon is a typical rocky body assigned to a non cometary status, yet swoops by the Sun every 1.4 years - much like a comet.