Ground Based Observation Working Group

In the frame of the BC mission, Earth-based observations of the exosphere have a crucial role in complementing the local observations. In fact, in-situ observations will always be very detailed but showing only a partial region of the Hermean exosphere and environment.

Earth-based observation on the contrary are able to provide the global view of the Hermean exosphere, though limited by the distance and by the geometry of the Earth and Mercury position along their orbits.

The role of the Ground Based Observation Working Group is to keep the scientific community of observers updated and linked to the Hermean Environment Working Group (HEWG) which of is a useful complement.

The role of the WG is to promote coordinated Earth based observations of the exosphere during the BC cruise and nominal phases (from now to 2027) and provide the scientific community with high quality data to implement in-situ measurements that will be performed by MMO and MPO devoted instrumentation, and help resolving the open questions on the exosphere generation, interaction and loss.


Primary Questions

  1. How does the ground based frequently observed N/S asymmetry (and dawn-dusk asymmetry observed during transits) merge with the MESSENGER results  showing a magnetic dipole offset, global seasonal variations of the exosphere and 'cold poles' enhancements?
  2. How does the (Na) exospheric interacts with the inner heliosphere events and nominal conditions to form the morphology and dynamics observed up to now?

Practical Questions

  1. What are the best suited telescopes and instruments on Earth and orbiting around it that can be used to provide new interesting observations?
  2. Can a new long-term international campaign of observations of Mercury exosphere be organized and supported through the years until Bepi Colombo reaches Mercury?

Meetings (most recent first)



1) Planned Earth-based observations of Mercury exosphere in 20209:

  • THEMIS observatory in Tenerife - Canary Islands (90-cm Ritchey-Chrétien alt-az evacuated telescope) led by Valeria Mangano (INAF, Roma): August 28th-Sept 6th (dusk terminator in view and disk at 90%) + October 1st-6th (dusk terminator in view and Mercury in 3rd quadrant of the orbit)


2019 observations & call for observers

1) Coordinated plan of Earth-based observations of Mercury exosphere in 2019:

  • Haleakala observatory in Maui- Hawaii (40-cm Schmidt Cassegrain telescope) lead by Shingo Kameda (Rikkyo University, Tokyo) : April 9-May 7 June 4 - July 11  August 1- August 19   September 24 - November 4 November 20 - December 13   February 2 - February 17  March 5 - April 20  (when Sun-Earth-Mercury angle is 15 degrees)
  • THEMIS observatory in Tenerife - Canary Islands (90-cm Ritchey-Chrétien alt-az evacuated telescope) led by Valeria Mangano (INAF, Roma): October 11-24 (dawn terminator in view and True Anomaly Angle between 170 and 240 - exact days to be confirmed)
  • DCT in Coconino National Forest - Arizona (4.3 m Ritchey-Chretien telescope) led by Carl Schmidt (University of Boston, MA) and Tom Bida : June 10-17 
  • ....TBC


2) Mercury transit in 2019: on November 11th a Mercury transit above the solar disk will occur between 12:35 and 18:04 UT and it will be fully visible in South America, North America (eastern coast) and on the Atlantic ocean, including Canary Islands (see for example:


3) An unofficial call is now open to look for new observers of the exosphere of Mercury. Please come and meet us at the next EPSC-DPS meeting in Geneva next September 15-20th, 2019, or contact us via email. 




Next meetings

Meet us at:

  • EPSC-DPS meeting in Geneva, 15-20 September 2019
  • Mercury 2020 Conference in Orleans (France), 2-4 June 2020
  • 2nd "Mercury Exosphere Ground Based Observations" workshop, to be held in early 2020 (date and site tbd) 



  • Valeria Mangano, INAF-IAPS Roma, Italy (email: name.surname at