Irish ESA astronomer will chase the eclipse in a plane from Dublin
3 August 1999What if it's cloudy on the morning of August 11? That is the question.Thousands, maybe millions of eclipse-lovers must now be worrying overthis dark thought. Well, here's something to make them feel envious.Irish ESA astronomer Leo Metcalfe will chase the eclipse whilst flying high through acloud-free sky, on board a plane that is likely to be one of thefirst meeting the lunar shadow. The plane will take off from Dublin andwill try to stretch the duration of the millennium's last eclipse by halfa minute, from 2 to 2.5 minutes. Not much, but enough to boost theemotion of a bunch of lucky adventurous scientists.
Irish ESA astronomer Leo Metcalfe, 40 years old, seems to devote himself to astronomical data... and nothing else. He spends his day buried in the archive of ESA's infrared space telescope, ISO, at ESA's satellite tracking station in Madrid, Spain. But appearances are deceptive. A lover of adventure, this astronomer has hired a jet that will depart from Dublin on the morning of August 11 to chase the last eclipse of the millennium.
"When you see a total eclipse the most impressive experience is that you 'feel' the shadow come over you at the same time that you see the Moon cover the Sun", he explains. "So you suddenly perceive as a direct experience the motion of the planetary bodies - Earth and Moon. It's a unique extension of the scale of normal perception. I'm looking to see how the experience is modified by being even more of a part of the dynamic aspect than an observer on the ground".
Metcalfe will try to stretch the duration of the eclipse from 2 to 2.5 minutes by flying within the lunar shadow. Other planes will do the same --the powerful Concorde will get 6.5 minutes of eclipse--, but the Dublin expedition might beat them all in at least one point: "We will intercept the shadow further West, and therefore earlier, than any other organised expedition I am aware of --though I'm open to correction", Metcalfe says.
Also, they will be able to fly higher than normal commercial airline flights --as high as 41000 feet if necessary-- to get above the clouds, which will guarantee them clear skies. According to estimates, observers on the ground in Western Europe have only about a 40% chance of having clear weather.
Metcalfe had the idea during last year's mid-Atlantic eclipse. He had missed that opportunity but would try next time. Although the August 11, 1999 total eclipse was scheduled to last only two minutes... Would it be possible to follow such a quick eclipse? He started to search for an airline. By december he had found a company, WestAir Ireland, willing to rent him a jet. The deal was made: the flight would be made with a Hawker Siddely 125 executive jet prepared to host 8 passengers plus the crew --two pilots and a flight assistant. Total price for a two-hour flight: 3700 Irish Pounds.
Expenses will be shared among the passengers: several astronomers, including Professor Brian McBreen, from University College Dublin, and possibly radio and science reporters. As of August 3 there are still some seats left.
Sharp turn to join the shadow
Comparing the eclipse track with the velocity of the plane Metcalfe has laid down the flight strategy. The expedition will take off from Dublin at about 09:15 Universal Time (10:15 local time) and fly West. The shadow will be intercepted not later than 45 minutes afterwards.
"So, we will enter the eclipse track flying towards the shadow", Metcalfe says. "We will be trying to see it come towards us over the sea from the horizon and I expect that we will see it. It will be approaching at 3600 kilometres per hour (1km per second). The shadow will be about 100 km wide and 135 km long on the curved surface of the Earth".
The main part of the trip will start when the shadow gets within about 1 minute of the plane. The pilot will then make a hard and fast 180 degree turn to join the shadow as it races over the Earth.
"This will be the high point of the trip, because we will level out flying with the shadow as totality begins. From our altitude we should see the totality as a dark circle around us. I asked the pilot if he can fly a fixed heading with non-zero roll angle - in other words, the plane will be tilted sideways in the sky to improve visibility towards the higher Sun angle".
From their privileged position astronomers might even be able to make some scientific observations, as this flight represents an opportunity to monitor dynamic phenomena such as the prominences in the solar corona --ejected plasma [ionised matter] swirling along the Sun's powerful magnetic field, like tongues of fire.
Metcalfe has promised a full graphic account of the show on his way back. So if you can't be one the passengers... at least you can watch what they watched!
Leo Metcalfe, Tel.: +34 91 8131372 (Until Friday, August 6) e-mail: lmetcalfiso.vilspa.esa.es
See also all other ESA contact points for the eclipse.