Astronomy

[Dreamwoven]

Space.com has a post on Ceres, wondering whether it can support life. This is the post: http://www.space.com/28068-dwarf-pla...l?cmpid=558748. Ceres is a dwarf planet, and a probe (Dawn) is heading towards it:

In March 2015, NASA's Dawn spacecraft will arrive in orbit around the dwarf planet Ceres, the largest object in the main asteroid belt between Mars and Jupiter. Ceres is a relatively warm and wet body that deserves to be mentioned in the same breath as the Jovian moon Europa and the Saturn satellite Enceladus, both of which may be capable of supporting life as we know it, some researchers say.

It occurs to me that this interest in whether a planet can support life is about planning a future spacecraft to go there and explore it. If life can be supported there a later probe might be to set up a base there. The nearer such a planet or (dwarf planet) is to earth the better.

There is a long Wikipedia item on Ceres, a dwarf planet. It is symptomatic of the turmoil in thinking about astronomy that the definition of this object has changed several times in recent history. See the Wikipedia item above which has a section devoted to the classification problematic. Planet, dwarf planet, asteroid, have all been considered by the International Astronomy Union, generally recognised as the world authority in such issues.

[YesNo]

I hadn't thought of labeling comets smelly or not, but it would be an amusing way to describe the gases coming from the comet. What is really interesting is that we can detect and identify those gases.

I also wasn't aware that Ceres might be able to support life. I noticed in the article that Gauss developed a quick method to predict the orbit of Ceres. I wonder what that method was. Also I noticed that if Pluto remained a "planet" then Ceres would have to be relabeled as a planet also.

[Dreamwoven]

We are still in the early stages of exploring the solar system. Pluto https://en.wikipedia.org/wiki/Pluto is the last of the outer planets we have still to visit. All visits so far have been preliminary with the exception of Mars, which has both ground and orbiting probes. Even that is still in its early stages.

Now at last the outermost planet (which as far as we know is Pluto, discovered in 1930, is about to be fleetingly passed by at an accellerated speed New Horizons after launch in 2006. The journey of 9 years is something of an epic in itself, needing several gravity assist loops around the Moon and Jupiter to build up speed.

Pluto is so far away from the sun that it takes 248 years to orbit the sun. So we only know approximately its orbit and speed.A bit like the early sail circumnavigators the flypass has to be judged accurately so as to come as close as possible without hitting the planet, so reasonable quality data can be collected.

If all goes well "On July 14, 2015, the Pluto system is due to be visited by spacecraft for the first time. The New Horizons probe will perform a flyby during which it will attempt to take detailed measurements and images of Pluto and its moons.[25] Afterwards, the probe may visit several other objects in the Kuiper belt.[26] (Pluto, Wikipedia)

[Dreamwoven]

Comet Lovejoy is showing well just now: http://earthsky.org/todays-image/wat...-comet-lovejoy . Europeans check out http://www.eagleseye.me.uk/Sky/Wordpress/?p=3527

[YesNo]

I hope I'll be able to see this. The skies are mostly cloudy here and when the clouds are gone then the urban lights make things difficult to see.

Out of my west window, the one I mainly look out from my home office, I have often seen Venus setting after the Sun.

[Dreamwoven]

I thought this was interesting from the Society for Popular Astronomy.

A CHRISTMAS COMET?
By Jonathan Shanklin, SPA Comet Section Director

There is a chance that Christmas will bring with it a binocular comet
that could even become visible to the unaided eye in the evening sky.
Terry Lovejoy, from Queensland, Australia, discovered comet 2014 Q2 on
August 16 with a CCD camera on his 0.2-m Schmidt-Cassegrain. Initially
of 15th magnitude, the comet has brightened quite rapidly on its way
to perihelion at 1.3 AU at the end of January. Currently visible from
the Southern Hemisphere as a 7th-magnitude object, it is moving
northwards and may become visible low down in the south just before
midnight on Christmas Eve. It continues to move northwards, and by
early January the comet will be visible in the early evening. It
should be at its brightest in mid-January and could remain visible in
binoculars until well into March. It is unlikely to show much of a
tail, but one of a degree or so in length might be seen with
binoculars. Interesting observing opportunities include the early
hours of December 29 when the comet is very close to M79, mid-January
when it is close to the Pleiades, and February 2 when it passes
between M 34 and NGC 752.

[YesNo]

Between January and March, that should give me enough time to spot it. I know where the Pleiades are, so I'll be looking in that direction.

Last night was partially overcast. I could make out a star or two if they were bright enough until the clouds covered them again.

[Dreamwoven]

The day before yesterday was meant to be a good day to see an aurora borealis display, a combination of high sunspot activity and clear skies. British newspapers reported widely on this with pictures. They were seen as far south as Newcastle, with blue and golden lights flashing. Here in Sweden we live at about the latitude of the northernmost Shetland Isles, at 66 degrees North, but saw nothing. Then again we did not go out, as it was -15 celsius that night. Can't stand about in that kind of cold.

[YesNo]

This has been the first clear evening in a long time. Although there is still light pollution where I live, I was able to find my way from Orion to Gemini, Canus Major and Taurus. In trying to find the names of the stars in the Pleiades (http://en.wikipedia.org/wiki/Pleiades) I noticed that there may be something wrong with the Hipparchus distance measurements:

The latest result (August, 2014)[21] used very long baseline radio interferometry (VLBI) to determine a distance of 136.2 ± 1.2 pc, conclusively showing "that the Hipparcos measured distance to the Pleiades cluster is in error." This demonstration of an unrecognized error in the Hipparcos data has implications for the similarly designed Gaia mission.

I thought Hipparchus results were the current best estimate.

[Dreamwoven]

Since Christmas Eve I have not been able to get outdoors to see the clear skies we have at nights. It has been -15 celsius here, and I have major heart problems, so I try to curb my impatience. I can see the Plough (I think its the Sickle in American) out of our one north facing windows. Not seen any of the dramatic aurora borealis yet either.

[Dreamwoven]

Comet Lovejoy looks to be showing well this month. I subscribe to Eagleseye (an Englishman's blog ) and just received a post just published which give some info and a picture of the comet.

[YesNo]

Based on that blog, Comet Lovejoy is in Lepus. Although the skies have clouded over, I'll see if I can at least find Lepus tonight.

[Dreamwoven]

The SOCIETY for POPULAR ASTRONOMY

Electronic News Bulletin No. 387 2014 November 23


TAIL DISCOVERED ON ASTEROID HYGIEA
Carnegie Institution

A new active asteroid, numbered 62412, has been discovered in the main
asteroid belt between Mars and Jupiter. It is the first comet-like
object seen in the Hygiea family of asteroids. Active asteroids are a
newly recognised phenomenon and 62412 is only the 13th known active
asteroid in the main asteroid belt. It is estimated that there may
be about 100 of them in the main asteroid belt. Active asteroids
have stable orbits between Mars and Jupiter like other asteroids;
unlike other asteroids, however, they sometimes have the appearance of
comets, when dust or gas is ejected from their surfaces, creating a
sporadic tail effect. Astronomers recently discovered a tail on
62412, an object which had been known as an ordinary asteroid for over
a decade. The reasons for the loss of material and the formation of a
tail in active asteroids are unknown, although there are several
theories such as recent impacts or sublimation from solid to gas of
exposed ices.

In the past, asteroids were thought to be mostly unchanging objects,
but an improved ability to observe them has allowed scientists to
discover tails and comas, the latter being like the thin envelopes of
atmosphere surrounding comets' nuclei. Discoveries such as this one
can help researchers to determine the processes that cause some
asteroids to become active. They found that 62412 has a very fast
rotation that may shift surface material, some of which may leave the
surface and form the comet-like appearance. The tail may be created
directly from material ejected from the fast-rotating body, or from
ice within it subliming into water vapour after being freshly exposed
on the surface. The density of 62412 has been found to be typical of
primitive asteroids and not consistent with the much lower densities
comets.

[YesNo]

I hadn't even considered that asteroids could have tails and that having tails made them "active".

I looked for Comet Lovejoy last night. I could barely make out the top of Lepus, but at least part of it was identifiable. I had to use binoculars to see the stars below Orion and then try to match the patterns with what I saw in the chart. It is warmer for me here, well above freezing. If it got to -15 degrees C I would not be out in it either.

I think I also found Jupiter. It was bright enough, but not quite where I expected it to be, but then nothing else seemed to fit since I could make out the constellations. I was looking for Leo and Cancer.

Viewing constellations along the horizon makes them seem larger than when they get higher. I also noticed the Hyades cluster around Aldabaran in Taurus. There were clearly more visible stars (through binoculars) in this location than around it, but it was not as compact as the Pleiades. Also the Orion Nebula looked like a fuzzy patch of light, suggesting there is more there than just a star.

[Dreamwoven]

Comet Lovejoy looks to be a visible comet this time round. Here is more info on it. I hope o be able to see it this time with binoculars.

A CHRISTMAS COMET?
By Jonathan Shanklin, SPA Comet Section Director

There is a chance that Christmas will bring with it a binocular comet
that could even become visible to the unaided eye in the evening sky.
Terry Lovejoy, from Queensland, Australia, discovered comet 2014 Q2 on
August 16 with a CCD camera on his 0.2-m Schmidt-Cassegrain. Initially
of 15th magnitude, the comet has brightened quite rapidly on its way
to perihelion at 1.3 AU at the end of January. Currently visible from
the Southern Hemisphere as a 7th-magnitude object, it is moving
northwards and may become visible low down in the south just before
midnight on Christmas Eve. It continues to move northwards, and by
early January the comet will be visible in the early evening. It
should be at its brightest in mid-January and could remain visible in
binoculars until well into March. It is unlikely to show much of a
tail, but one of a degree or so in length might be seen with
binoculars. Interesting observing opportunities include the early
hours of December 29 when the comet is very close to M79, mid-January
when it is close to the Pleiades, and February 2 when it passes
between M 34 and NGC 752. There is a finding chart on the SPA web
pages. Making a sketch is a good way to train the eye to see faint
features in astronomical objects, and those of a diffuse comet tail
are often particularly subtle. Spend some time getting fully
dark-adapted, then try looking a little bit away from the comet, but
keeping it in your field of view. That technique of 'averted vision'
sometimes allows you to see faint objects that cannot be seen when
looked at directly. Do send me your observations, which could include
magnitude estimates, drawings, written descriptions or images.