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## Venus and Mars in conjunction on February the 21st

On Monday (the 16th) I am going to be on live TV talking about the conjunction of Venus and Mars, which will happen on the 21st (Saturday). In the western sky, just after sunset, you will see Venus and Mars come very close together, and it is this chance alignment as seen from Earth that we call a conjunction. Venus, for anyone who has been looking at the evening sky of late, is very very bright at the moment just after sunset. Mars, on the other hand, is much fainter, but knowing it is close to Venus this next week to ten days will help you find it.

The diagram below, which is a screen capture using SkySafari on my iPad, shows the sky at 6pm (18:00) as seen from London on Monday the 16th. As you can see, Venus is very bright and Mars is much fainter, at about 11 o’ clock to Venus if you imagine the face of a clock.

The positions of Venus and Mars at 6pm (18:00) on the evening of Monday the 16th of February, as seen from London.

Both planets are currently in Pisces, and Venus is approaching the brightest it can be. It has a magnitude of $-4.0$ this week (for an explanation of the magnitude system, see my blog here). Mars, as is obvious from the diagrams and if you look yourself, is much fainter; currently $+1.3$, making it $10^{0.4(1.3+4.0} = 131.8$ times fainter! A magnitude of $+1.3$ makes Mars easily visible, but it doesn’t jump out at you like Venus does.

The positions of Venus and Mars at 6pm (18:00) on the evening of Thursday the 19th of February, as seen from London.

The positions of Venus and Mars at 6pm (18:00) on the evening of Friday the 20th of February, as seen from London.

The positions of Venus and Mars at 6pm (18:00) on the evening of Saturday the 21st of February, as seen from London.

If I zoom in a bit for a couple of these evenings, this is how things will look

The positions of Venus and Mars at 6pm (18:00) on the evening of Friday the 20th of February, as seen from London.

The positions of Venus and Mars at 6pm (18:00) on the evening of Saturday the 21st of February, as seen from London.

To the naked eye, Venus and Mars will not be separable, but through binoculars or a small telescope you will be able to see enough detail to be able to see the small angular distance between them.

One of the theories for what the star of Bethlehem was (if it existed at all, and assuming it was not supernatural), is that it was a triple conjunction of Mars, Jupiter and Saturn. Modern sky simulation software has allowed us to show that this happened in 7 B.C., but it shouldn’t come as any surprise to anyone who knows their history that Jesus could not have been born after 4 B.C. because that is the year King Herod died. A conjunction between Venus and Jupiter, the two brightest planets, can be very spectacular.

## Comet ISON update

I was on the S4C programme “Heno” talking about Comet ISON on the 26th of November, just two days before its perihelion (closest approach to the Sun). I was the studio guest, so I appeared on the programme right at the beginning, then at about 8 minutes into the programme, and finally at the end. Here is the entire programme with subtitles (if you can bear it).

Here is an edited version, with just the parts of the programme where I appear :

It would seem comet ISON did not survive its passage around the Sun. All the evidence suggests that ISON broke up as it came within about 1.5 million km of the Sun, probably due to the nucleus of the comet being broken up by a combination of the heat of the Sun and the extreme tidal forces due to the Sun’s gravity. Here is a link to images of ISON at the time of its perihelion taken by the NASA Stereo Probes’ (which are in space observing the Sun)

The latest efforts now concentrate on trying to find ISON’s remnants and to understand in more detail what happened to the comet. You can read more about this in this story.

So, sadly, we did not get the spectacular cometary display in early December that many had been hoping for. But, that is the nature of comets, and part of their fascination. One never knows how they are going to turn out, they are very unpredictable and often surprise us. ISON proved ultimately to be a disappointment, but already there are other comets that astronomers have their sights on which may come and light up our skies over the next few months, such as Comet Lovejoy.