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Transit of Mercury, 9 May 2016

The Institute of Cosmos Sciences of the Universitat de Barcelona (IEEC-UB) with the Quantum Physics and Astrophysics Department will broadcast the event on internet and will organize several activities in the street.
Webcast and activities cancelled due to bad weather


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Transit Proba 2 2.jpg
Video of the Transit of Mercury
Proba-2 (ESA), SDO (NASA)

transit Mercu6en 2.jpg
Live Webcast
Cancelled due to bad weather

TM2016May09 Mapca.jpg
Transit information

Public viewing
Cancelled due to bad weather

How can we observe the transit?

comicTM2016A4 eng.jpg

Composició en la qual es veu una bona part del Sol, amb una gran taca irregular a la part inferior esquerra de la imatge i unes altres, una mica més petites i molt més redones, en la part superior dreta del Sol: el planeta Mercuri en diferents moments del trànsit
What is a transit?

Retrat del capità Cook
Transit History

Frequent Asked Questions

Transit on the Radio (catalan)


On 9th May a transit of Mercury will be visible from Catalonia. The transit will begin at midday and will end with the sunset.

The transits of Mercury cannot be seen with the naked eye. You need a telescope for a good observation.

Remember NEVER LOOK DIRECTLY TO THE SUN. Projecting the image is the best option to see the transit.

Broadcast will follow the Transit from its beginning at 11:12 TU to its end at 18:42 TU.

Proposed Activities

To the general public and educational centers:

Activities available in Catalan, Spanish and English (registration is necessary)


  • Public observation: two telescopes will be placed at Palau Reial, Diagonal Avenue, Barcelona.
  • It will be explained the Transit phenomenon in general and this Mercury transit in particular to the registered groups
  • It will be shown how to observe the Sun following the projection method

Activities Timetable:

It will be reserved to the groups an hour sessions from 13:00 to 18:00 (oficial time)


Groups who want to participate in the proposed activitie shoud send a e-mail in order to set the time and the number of attendees:


In order not to create great expectations to the public less experienced with the astronomical observations, we should advice that a Mercury Transit it is not a spectacular event despite being very interesting and beautiful from an astronomical point of view. Mercury is so small that we can't observe it with the naked eye, and the transit duration makes its movement only perceptible if we observe for a while. You should not to hope an event as astonishing as an eclipse.

Physics Faculty Students

Transit observation from the Faculty roof

Transit information

Observation times

During a transit we can distinguish some remarkable moments:

  • Contact I, or external ingress: the instant when the planet's disk is externally tangent with the Sun.
  • Contact II, or internal ingress: the instant when the planet's disk is internally tangent with the Sun. The entire disk of the Venus is first seen.
  • During the next several hours, Venus gradually traverses the solar disk at a relative angular rate of approximately 4 arcmin/hr.
  • Greatest transit is the instant of minimum angular separation between Venus and the Sun as seen from Earth's geocenter.
  • Contact III, or internal egress: the instant when the planet reaches the opposite limb and is once again internally tangent with the Sun.
  • Contact IV, or external egress:the instant when the planet's limb is, similarly to contact I, externally tangent to the Sun but at the opposite side of the Sun. The transit ends at this contact.
The observation times of the transit in Universal Time:

Contact I 11:12:18 UT
Contact II 11:15:30 UT
Greatest 14:57:25 UT
Contact III 18:39:12 UT
Contact IV 18:42:24 UT

Global Visibility

The transit is not visible everywhere on Earth. Depending on the altitude of the Sun in a place during the event, the transit will be entirily, partially or not at all visible.

This map represents the visibility of the transit over the world.

TM2016May09 Mapca.jpg
  • The transit is already in progress at sunrise for observers in the Pacific and the west of America.
  • The four contacts will be visible from a great part of South America, the east of North America, Greenland, the Atlantic, the west of Africa and the west of Europa.
  • The Sun sets while the transit is still in progress from the east of Europa, the most of Africa, and the most of Asia
  • No portion of the transit will be visible the east of Asia, Oceania and Antarctica.

How can we observe the transit?

NEVER LOOK AT THE SUN DIRECTLY. Looking at the Sun directly without protection or trough eyeglasses (including sunglasses), telescopes or any other instrument not designed for solar observation may result in severe eye injury and blindness.

Because of the small apparent size of Mercury, it will be impossible to observe the planet's disc during the transit unless aided with an optical instrument (ALWAYS UTILIZING A SOLAR FILTER). The safest way to observe the transit is by projecting the image of the Sun trough a telescope onto a white screen (see figure below). In addition, this procedure permits the simultaneous observation of the phenomenon to a group of people.

However, the projection method will yield a better viewing of the event.


31 4840.JPG

Projection of the transit of Venus 2004

What is a transit?

A transit is the crossing of a planet or any celestial object in front of the Sun. Mercury and Venus are the only Solar System planets that can give transits, because they are closer to the Sun than the Earth. The Moon can also give transits, and in this case the phenomena is called a Solar eclipse.

During a transit the disk of the planet is seen projected on the bright surface of the Sun.
Composició en la qual es veu una bona part del Sol, amb una gran taca irregular a la part inferior esquerra de la imatge i unes altres, una mica més petites i molt més redones, en la part superior dreta del Sol: el planeta Mercuri en diferents moments del trànsit
Composition of pictures of the transit of Mercury 7-05-2003.

When did the last transit take place?

The last transit of Mercury was on November 15, 1999. This transit, however, was not visible from Europe during any of its phases. The last transit visible from Europe occurred on November 10, 1973.

When will the next transits occur?

The next transit of Mercury will be on November 11, 2019 and from the mainland will be visible only in part, because the sun will set before the transit finished.


An overview of the transits of the last centuries. Click here

Comic of the Transit

comicTM2016A4 eng.jpg

The transit of the 2003.

Special page of Serviastro about the transit of Mercury of the 7th of May 2003 and its broadcast. Click here

Frequent Asked Questions

The most asked questions about planetary transits and the transit of Mercury. Click here


Informació general

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