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Occultation of Venus of June 18th 2007


Do not observe the Sun directly, neither with the naked eye nor with any kind of instrument.

General description of the occultation

Venus is the third most brilliant object of the sky, following the Sun and the Moon. Surely, everybody has seen it thousands of times in the sky, always near the Sun: sometimes in the western sky, during and immediately after the sunset; sometimes in the eastern sky, over the sunrise, until the moment when the powerful brightness of the Sun makes it disappear from the sight of almost everyone of us.

Indeed, most of us would finally lose sight of the planet Venus after the sunrise, but some of us would still be able to follow it. In fact, Venus is such a bright object that anybody can see it in broad daylight if its exact position is known The problem is that to find it is usually very and very difficult.

The 18th of June will be an exception: Venus, with a magnitude of -4.4, will be very near the Moon, in such a way that it will be enough to look for our satellite and then the only bright dot observable around it - a bit to the east - will be Venus. Both objects will be so near that the Moon will occult Venus for nearly a whole hour to observers from Barcelona!

Moreover, the situation of the sky as a whole will be especially appropiate for the observation of this occultation:

  1. Venus will have passed through the position of greatest eastern elongation on June 9th, so it will still be far from the Sun and its light will not difficult the observation.
  2. The Moon is new on June 15th, so on 18th it will still be in a light crescent phase: only the 15% of the lunar disc will be illuminated (phase of 0.151). Then, its brightness will not be annoying for observers and photographers.

Aspecte global de l'ocultació del 18 de juny de 2007 vista des de Barcelona.
Global picture of the occultation of Venus on June 18th as observed from Barcelona.
The image has been obtained by members of Serviastro with the free software program Celestia

Aspecte global de la reaparició el 18 de juny de 2007, vista des de Barcelona. Global picture of the reappearance on June 18th as observed from Barcelona.
The image has been obtained by members of Serviastro with the free software program Celestia

With the naked eye, the planet Venus will be seen thanks to the Moon - as we have already said - and to observe the process of occultation by the eclipsed side of our satellite and of reappearance from behind the brighter side will also be possible. There are no excuses - if the sky is clear enough: wherever you will be, just by looking up to the sky you will enjoy the sight of this event!!

On the other hand, to appreciate the occultation in detail it should be observed through some kind of instrument. Recall not to look directly to the Sun!! Doing it with the naked eye blinds us for some minutes and with a magnification instrument and no protection we could suffer serious injuries in our eyes. With a high magnification binocular, some details could be appreciate if it is fixed to avoid the annoying vibrations which usually affect the observation when it is hold with the hands. Anyway, a telescope - if available - is always a better option.

Who observe with instruments of this class, will completely enjoy the event:

  • Firstly, it will be much easier to observe the exact moments of desappearance and reappearance of the planet. Given the distance between Venus and Earth in that moment, the apparent diameter of Venus will be of 26.41 arcseconds and so, the Moon should take over 1 minute to cover, and another one to uncover, it completely.
  • Nevertheless, who observe the occultation and measure this interval will be surprised: that it is, more or less, the half of what is predicted by the foregoing considerations will be found. The explanation of this apparent contradiction is that Venus will be passing through one of its phases!, as everyone who use a telescope will see.

Inferior planets (Mercury and Venus), when observed from Earth, pass through phases - like the Moon does, being their cycle very different. In the very moment of the occultation, on June 18th, Venus will be passing a crescent phase of the 44%.

Finally, if you can observe the event in detail with a telescope, you will see something like this:

Imatge en detall de l'ocultació vista des de Barcelona, amb Venus clarament en fase creixent
Detall de l'ocultació de Venus del 18 de juny de 2007 vista des de Barcelona en el qual s'aprecia la fase creixent de Venus.
La imatge ha estat obtinguda per membres de Serviastro amb el programa de codi lliure Celestia

Dades tècniques: des d'on i quan podrà observar-se?

Les ocultacions són fenòmens astronòmics que, a l'igual que els eclipsis de Sol, només poden observar-se des de determinades franges de la superfície terrestre i la seva aparença és molt diferent si s'observen des de llocs diferents. En aquest cas, podrà observar-se des de determinades zones d'Amèrica del Nord (en ple dia), fins a l'Índia durant la nit, passant per tota Europa - excepte la zona sud-oest de la Penínsual Ibèrica - i l'Orient Mitjà, on també podrà observar-se a plena llum del dia.

Mapa de les zones on l'ocultació de Venus serà observable

Detailed image of the occultation as observed from Barcelona, with Venus clearly passing through a crescent phase.
The image has been obtained by members of Serviastro with the free software program Celestia

Technical data: from where and when it can be observed?

Occultations are astronomical events which, as well as solar eclipses, can only be observed from certain strips of the earth surface and whose appearance changes a lot with position. In this case, it can be observed from certain areas of North America (in broad daylight), to India during the night, passing through the whole Europe - except the southeast of the Iberian Peninsula - and Middle East, where it will also occur in broad daylight.

Map of the area where the occultation of Venus will be visible
Map of the area where the occultation of Venus will be visible.
Dotted line: occultation during the day.
Continuous line: occultation during twilight.
Bold line: occultation during the night.
Courtesy: IOTA

About the exact moment of the event, it is advisable to visit the page that the IOTA has published , with data over the whole strip of visibility. We only give data for some spanish cities from which the occultation will be observable:

Take into account that the following data are just a forecast. Given the short duration of the event (of the intervals of desappearance and reappearance), we strongly recommend to start the observation a while before the forecast time.

Disappearance Reappearance
Barcelona 14:32:16 UT 15:24:13 UT
Santiago 14:22:09 UT 14:46:11 UT
València 14:47:45 UT 15:04:23 UT
Valladolid 14:30:57 UT 14:55:57 UT

Attention!!: Recall that we are in summertime and so we go two hours forward the universal time, in Spain.

Gallery of images

You can check that this event on June 18th will be really wonderful. Do not doubt: observe it and take photographs with the available instruments you have! Then, we will be pleased to post what you sent on this page.


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