Star of Bethlehem?

There was an article on MSNBC.com indicating that Jupiter and Venus appeared so close in the sky on 17 Jun 02 BC that they would have appeared as one bright star.  Since the program Redshift 5 has the ability to show the sky at any time in the past or future, I set it up to go back to that time and see what this event would have looked like.  I was rather astounded.  Venus and Jupiter, as seen from the earth, appeared to be phenominally close together.  Now of course Venus is closer to the sun than the earth and Jupiter is farther from the sun than the earth but they can become aligned so that from our vantage point on earth they appear to be close together in the sky within a couple of hours after sundown or a couple of hours before sunrise.  It is not uncommon for planets to be aligned so as to appear close to each other but in this case, they appeared to be VERY close to each other.  Extremely unusual.  If such an event were to occur in our lifetime, amateur and professional astronomers would undoubtedly flock to the site so they could observe and photograph it.

I set up Redshift to show the "Universal Time Coordinated" (UTC - essentially London time) and noted that Bethlehem time is two hours ahead of that.  I set up Redshift 5 so that it would show what an observer in Telaviv would have seen (about the same as what an observer in Bethlehem would have seen - I know the coordinates of Telaviv and am not as sure of the coordinates of Bethlehem so that's why I chose Telaviv.)  I then created a time-lapse movie of the event that covers about 2.5 hours of the event from where the sky first becomes dark enough to see the two planets until they go below the horizon.  Redshift 5 can be set up so that it colors the sky to approximate what an observer would see.  It changes from blue to dark as twilight wanes.  The other round objects in the view are the moons of Jupiter.  These images are what you would see through a 227 power telescope.  Without a telescope, the two planets would appear to be one object - A bright object that would look like a single bright star.  An interesting thing is that the previous night, the two planets would have been far enough apart that they could never have been mistaken for a single object.  It is the same on the following night since the planets by then have moved far apart.  It is only on this one night and only from this longitude, plus or minus a couple of time zones, that this event would have been visible to anyone on earth.  From Bethlehem, the closest approach is during twilight.  The two planets would still look like one bright star until they passed below the horizon.  Further to the East, Baghdad for example, the pair would be lower in the sky but the closest approach would be after twilight in a very dark sky.  This event might have attracted the attention of anyone making careful observations of the night sky.  It might seem that both Jupiter and Venus disappeared from the sky and a new bright star appeared instead.   This bright star would appear to be in the West and persons East of Bethlehem might have been intrigued enough by it to set out on a journey because of it.  However, Redshift 5 shows the magnitude of Jupiter at that time to have been -1.63 and the magnitude of Venus to have been -4.23.  If my calculations are correct, the resultant magnitude of the combined object would have been only -4.40, hardly enough to attract much more attention than Venus itself?  So I guess I am still skeptical as to whether this was the Star of Bethlehem but it is intriguing...


Venus and Jupiter From Telaviv - 17 Jun 02 BC - from dusk until they go below the horizon - Magnified 227 X


Venus and Jupiter From Baghdad - 17 Jun 02 BC - from dusk until they go below the horizon - Magnified 227 X

Note that in the above images, the time interval between frames is 10 minutes.  We are displaying them at 2 frames per second so that we can see the motion speeded up.  The text in the top left corner shows the UTC date and time (London time) and the altitude in degrees above the horizon is also shown.  Each movie runs from when the planets first become visible during twilight until they pass below the horizon. 


Copyright 2004 Howard C. Anderson
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