February night skies and Unseen Blackholes




Blackholes, as the name suggests, sound a bit frightening.  One may imagine a hole in the ground that is so deep, without a bottom, where the only thing you can see nothing but blackness.  But, can you "see"  blackness?  Blackness is a lack of light, which means no visible light is coming from the bottom of the deep well.  So when you "see" black, the fact is that you are seeing nothing!


The astronomical blackholes get their name from a similar effect - no light can come out of a blackhole.  Light is of many types, some visible (like the blue, yellow, white light that we see) while others are invisible (like the heat rays from the side of a hot stove, the radio waves, the X-rays).  A blackhole does not allow ANY light, visible or invisible, to go out of the blackhole. Since light is the fastest thing in nature, this means that NOTHING can escape from inside  a blackhole.  The radius from which nothing can escape, not even light, is called the event horizon.


The idea of blackholes was first put forward in the late 1700s and was developed as the life cycles of stars continued to be understood using Einstein's theories. Blackholes were found to be one of the possible final products when stars end their lives.  Stephen Hawking, a completely physically invalid scientist who communicates with using computer technology, explained the physics of blackholes in 1970. 


Since the only way that we have of knowing about things that are so far away from us is by measuring radiation that we receive from that object.  But a blackhole does not allow any light to escape from it. So we may ask, can we ever see a blackhole? 


Blackholes  were first discovered by their indirect effect through gravitational attraction of material from nearby stars. As the material circled and fell into the blackhole it gave off X-rays which could be detected from Earth.  The first such evidence of a blackhole was found in 1972 from the Cygnus X-1 blackhole.


In 1974 Hawking calculated that due to quantum effects (i.e. due to the behaviour of matter at subatomic level), radiation can be emitted from the event horizon (see above).  However, the radiation is very weak and not easy to detect from Earth.


Hawking made headlines last month when he pronounced that "there are no blackholes with a definite event horizon below which nothing can escape", which the media took to mean that "black holes don't exist".  This caused a stir in public about science  because something that had been proved to exist by such an eminent scientist (Hawking) was now being denied by the same scientist, thus putting doubts on all conclusions of science, including the global warming catastrophe that is upon us.


It turns out however, that it is completed unfounded to doubt truths revealed by science.  Hawking was implying that due to quantum effects the event horizon is not fixed hence something can escape a blackhole.  But the energy that escapes is in such a mixed up form that the information that comes out of a blackhole has no relation to the information that was sucked into it in the first place.  Hence the blackholes remains just as black, and they do indeed exist!


Among the night sky delights that we can enjoy this month is Jupiter in Gemini which is brighter than the brightest star Sirius and the second brightest star Canopus.  These three form an almost straight line that can be seen almost directly overhead around 9 pm in the Gemini constellation.


Early risers can enjoy brilliant Venus in the East just before sunrise.  It continues to climb higher in the sky and become brighter as its shape through a telescope changes from the current crescent shape to half phase at highest elevation, of around 40 degrees, by the end of March.


Mars enters the early night sky this month in the east around 10 pm.  It can also be seen high in the sky just before sunrise.  It is relatively faint but a distinctly see as a red point that does not twinkle.  It is in retrograde motion at the moment, moving westwards towards the bright star Spica which is the brightest star in Virgo constellation.  It will continue to brighten to deep red until it reaches maximum brightness in early April.

Saturn is also a morning planet and enters the evening skies around the beginning of next month.  Just before sunrise Saturn can be seen almost overhead.  Get more and  recent details  from the Astronomy In Tanzania  website: http://www.astronomyintanzania.or.tz


The Moon is never New this month, having passed through the New Moon phase on 30th January and the next one being on  1st March.  Hence the Full Moon occurs exactly in the middle of the month on  14th February, the  Valentine day.

The early evening night sky cut across by the dense collection of stars and interstellar clouds of the Milky Way band running from south to north. The constellations within the path of the Milky Way are CANIS MAJOR (the big dog) with its brightest star Sirius, ORION (the hunter) with its numerous nebulae and the red giant Betelgeuse, TAURUS (the bull) which has two star clusters, Hyades and Pleiades and the red giant star Antares. 

The PERSUS (son of Zeus) constellation contains the famous Andromeda galaxy that is two million light-years away but can be seen with the naked eyes in dark skies as a cloudy patch.  Finally the W shaped CASSIOPEIA (the queen) is in the north. A new addition this month is the FALSE CROSS, an asterism that closely resembles the kite shaped SOUTHERN CROSS but whose long diagonal does not point south. Locate it after 9 p.m. as it rises in the southeast. LEO (the lion) raises its head in the east at 8 p.m. and should be easily recognizable by 9:30 p.m.

Five of the top ten brightest stars can be recognized using the star map: The brightest star is Sirius in Canis Major, second brightest is Canopus towards the south. Rigel is in ORION , Procyon is to the east of Orion, Achernar will be setting in the southwest and Betelgeuse is in ORION. After 10 p.m. they will be joined by Alpha- and Beta-Centauri, the bright vertical pair stars rising below the SOUTHERN CROSS.

The International Space Station (ISS) will be clearly visible on 2nd March and even better on 3rd March. On 2nd it will rise in the northwest at 8:03 pm move towards the southeast parallel and to the west of the Milky Way.  It will reach the highest elevation at 8:06 pm and will disappear suddenly from view a few seconds later as the satellite enters the shadow region.  On 3rd March the ISS will rise, again, in northwest at 7:14 pm, and will follow the Milky Way to its east. It will reach maximum altitude at 7:17 pm and will set in the southeast horizon at 7:20 pm.  More up to date  timings  for specific location can  be obtained from their website http://www.heavens-above.com and entering  the  coordinates of your location.


The global Globe at Night campaign to reduce ligtht pollution and conserving dark skies, takes place this month from 19-28 Febaruary and for March it will be done from 21-30.  During this time, measurements of light pollution are done by comparing stars that are not visible in polluted skies and comparing them to  star charts of skies without light  pollution.  The data are collected centrally via their website http://www.globeatnight.org