The red planet Mars can be seen each morning before dawn in the north-eastern sky. Tomorrow morning the crescent Moon acts as a signpost to locate the planet as it is above and to its left or north. On Thursday morning the Moon appears closer to the planet and is still above it, but is to its right or east.
Mars and the Moon with nearby stars on the morning of 27 November 2013. Chart Nick Lomb
The colour of a star indicates its surface temperature. The hottest stars glow blue-white with temperatures of 30,000-40,000° Celsius. White stars are about 10,000° C, while the coolest are the red stars with temperatures of around 3000° C.
A plot of the temperature or spectral type of stars against their brightness shows the position of different groups of stars. The hottest stars are to the left and the cooler ones are to the right. Courtesy Wikimedia Commons
NASA launched one of the earliest weather satellites TIROS 2 on this day in 1960. Its name stood for Television and InfraRed Observation Satellite as it had two television cameras and two infrared detectors for observing clouds and atmospheric phenomena. The 127 kg satellite helped to prove the value of such spacecraft.
A cross-sectional view of the TIROS satellites. Courtesy NASA
We see most stars as white because our eyes are poor at seeing colour in the dark. Colour is only obvious to the naked eye for a few of the brighter reddish stars like Betelgeuse in Orion. Photographs reveal a greater range of colours for stars including ones that are blue-white, white, yellow and red.
The constellation of Orion with the star Betelgeuse labelled. Photo Nick Lomb
Early risers can see the giant planet Jupiter in the northern sky before dawn. Although much further from the Sun and the Earth than bright Venus, Jupiter currently appears only a little fainter. Tomorrow morning the gibbous Moon is above and to the left or west of Jupiter, while on Saturday morning it is still above but to the right or east.
Jupiter and the Moon on 22 November 2013. Chart Nick Lomb
The much talked about Comet ISON is now racing towards its close approach to the Sun on the early morning of 29 November 2013 (Australian time). It has brightened somewhat in recent days, but as yet scientists do not know how bright it will be before and after that close approach nor whether the comet will survive its encounter with the Sun. Over the next few mornings it may still be possible to view the comet in the dawn sky (for where to look please see this previous blog post), but it is getting increasingly difficult as it gets closer to the Sun. After the encounter with the Sun the comet moves into the northern sky and out of view for those of us in the southern hemisphere.
The Comet ISON interactive model provides an excellent visualisation of the path of Comet ISON as it approaches and then passes the Sun. Courtesy Michal Sadlon.
The Sun on 17 November 2013 showed lots of spots including some large ones, but AR11890 discussed in this post had rotated out of view on the western edge of the Sun two or three days earlier. The main sunspots are identified in this image with the extra 1 removed from the front of the number for clarity. Photo Nick Lomb
The parade of spots across the Sun is a majestic sight – but may give the impression that all spots are ‘new’, and making their first transit – in fact a percentage are making their second or even third return. The positions of new spots are routinely calculated and often reveal the ‘returnees’.
AR11861. Back in 2013 October 7th a modest pair of spots was logged in the Sun’s SE: the preceding spot (p) was smaller and sited at –10,174, the larger follower (f) was at –10,167. There was nothing unusual about this group except that the (f) spot was larger than the (p): a reversal of the norm.
It duly rotated across the disc until on the 11th new spots began to emerge between the two main ones, briefly ‘welding’ them together as a mixture of polarities in one fairly large penumbra (Fig, inset lower left). The newly emerged flux caused NOAA to upgrade the group’s magnetic class to Beta-Gamma-Delta – and M class flares began. At this time I was restricted to a small 72/500 WL ‘scope and no H-alpha logs were made.
By the 17th more new spots emerged causing AR11861 to fragment into several elongated penumbrae with many spots spread over 13º of longitude – and it rotated out of view next day. I was not expecting a return: perhaps I should have!
Four views of Sunspot AR11890 in early November 2013. Sketch and copyright Harry Roberts ©, all rights reserved
AR11890. By Dec 2nd (UT) the long focal-length ‘scope was back in use and showed a group of irregular spots rounding the eastern limb: irregular shapes imply magnetic complexity. The heliocentric coordinates of new the group soon showed that 11861 had returned – and was soon dubbed AR11890 (Fig, Log1).
The figure shows four logs of 11890 and one of 11861 (inset) for comparison. We see that the preceding (p) spot of 11861 was sited at –8,172 and that of the new group at –9,174: essentially identical, allowing for a small migration of the (p) spot westwards over time.
The following (f) spots of the two groups tell a similar story. AR11861’s (f) spot was at –6,166 on Oct 11, but by the time of western limb passage had evolved (due to flux emergence cited) to –11,159 on Oct 17 – when the group was then 13º in length (not shown). As the (f) spots of AR11890 are about -12,165 there is no doubt it is the return of 11861: the positions are identical.
The big change in 11861 since Oct 17 lay in its magnetic complexity: elongated and triangular shaped umbrae are seen in Logs 1 and 2. Clearly major remodelling of the group happened during its ‘farside’ transit with new (f) spots emerging a bit to the south of the (f) spots of 11861.
Spot emergence. Visible again, the group changed shape daily: the irregular shapes of Logs 1 and 2 grew rounder –as in logs 3 and 4. As well many new spots emerged, with 40 counted on the 5th and about 50 on the 6th – when its area grew almost to 1000units – a very big group.
GOES X3.3 flare. The emergence of new spots (i.e. flux) implies flares, and while the white-light log was being made on the 5th an X3.3 flare erupted. When H-alpha was again fitted at 22:30 it had almost faded, though a bright ‘strand’ (Log3, red) warned me that I’d missed something big (again!)
The GONG H-alpha network showed the full extent of the X3.3 and it is dotted (in red) on log3. This was a big flare – the strongest so far for a southern group in SC24. This may suggest that the southern hemisphere is nearing its maximum – while the north likely peaked back in 2011. Only time will tell.
Strongest flares. Recall that the strongest flare of SC24 thus far is the X6.9 in northern group AR11263 on Aug 9, 2011 – and the second strongest an X5.4 in Mar 2012.
The X3.3 flare in 11890 was the third strongest for this cycle. Perhaps this means that southern activity is rising and we may expect more even stronger flares in that hemisphere in coming days.
Returnee. While returnee sunspots are not uncommon – ones that are bigger with much stronger flares the ‘second time around’ are rare. Will 11890 survive to return once more at the end of November? Keep a close watch on the Sun’s southeastern limb.
Harry Roberts is a Sun and Moon observer, a regular contributor to the Sydney Observatory blog and a member of the Sydney City Skywatchers.
The bright planet Venus can be seen shining brightly in the western sky each evening soon after sunset. Tonight it passes within half a moon-width of the star with the Babylonian name of Nunki in the handle of the Teapot, which is how many people see the classical constellation of Sagittarius the Archer.
Venus and the star Nunki on 19 November 2013. Chart Nick Lomb
US Astronaut Alan B Shephard, Jr was born on this day in 1923 in East Derry, New Hampshire, United States. After service as a test pilot he was chosen as one of the Mercury astronauts in 1959. Two years later be became the first American into space when a Redstone rocket took his Freedom 7 capsule on a suborbital ride.
Alan B Shephard, Jr. Courtesy NASA
These are the constellations the Sun passes in front of during the year. Looking from west to east in the early evening the following zodiac constellations are visible: Scorpius, Sagittarius, Capricornus, Aquarius, Pisces, Aries and part of Taurus.
The planet Venus currently shows the position of the constellation of Sagittarius in the evening sky. Courtesy Stellarium software