If you’ve seen Totality many times, consider going to the edge of the eclipse track for some unique phenomena
‘Go for the centerline’ has almost become a mantra for August 21. At the moment of Totality on August 21 eclipse chasers with experienced syzygy – the lining up of Sun, Moon, Earth, and you – but why settle for that celestial sync?
Using the very latest data it’s possible to place yourself almost exactly in line with the Moon’s mountainous South Pole. But to do that, you have to head right to the edge of Path of Totality, also called the ‘graze zones.’
Why would anyone want to do that?
What you will see during Totality is going to depend on your location,”
says Bob Baer, staff member at SIU Carbondale Physics Department, which is right on the centerline on August 21. “Xavier Jubier has these great predictions – he’s now able to predict Baily’s Beads in advance because of the highly accurate lunar limb data he’s using in this maps.”
Seen at seen at 2nd and 3rd contacts, Baily’s Beads are beads of the only remaining visible sunlight pouring through the valleys of the Moon. Just before the Sun is completely blocked, the last rays create a magical Diamond Ring around the Moon that signals the start of totality. Both last much longer if you stand near the edge of the Path of Totality. “It depends on what you want,” says Baer, who will be collecting data for the Citizen CATE experiment. “I’ve heard from eclipse-chasers that when they observe from the edge they get extended diamond rings and they get awesome Baily’s Beads,” he says.
The time in Totality is not as long, but they get those features that you don’t see from the centerline.”
It’s a big compromise; right on the edge we’re talking a few seconds or so of Totality, compared to the two minutes+ offered about 30 miles north. I say north, because ‘edgy’ eclipse-chasers should try to position themselves near the southern limit of the eclipse track to get the effects they’re after.
“Baily’s Beads at the northern edge of the eclipse track are caused by the terrain at the Moon’s North Pole, which is flat compared to the considerably southern mountains at the South Pole,” explains Paul D. Maley of the NASA Johnson Space Center Astronomical Society, who organizes astronomy tours worldwide for Ring of Fire expeditions. “Baily’s Beads are prolonged because of the tangential motion movement of the Moon’s edge alongside that of the Sun’s edge slows everything down,” he says.
If anyone is going to see prolonged Baily’s Beads, it will be people at the southern edge.”
Viewers at the edge also get a prolonged view of prominences, and longer diamond ring.
Maley is taking a group of about 100 people to Grand Island, Nebraska, but he’s organised a school in Minden, Nebraska – right on the southern limit of the eclipse track – to make observations of Baily’s beads and the diamond ring.
However, the edges of the Path of Totality are the dividing lines between seeing and not seeing a Total Solar Ecclipse. “People on the edge will not see much of anything of the total eclipse so if they see anything it will be maybe a few to maybe 30 seconds of totality,” says Maley.
It’s for that reason that such edgy behaviour is not recommended for most people who want to enjoy as much Totality as possible.
First time observers should go close to the centreline,”
says Baer, who will himself be in Carbondale, bang on the centerline.
“But after you’ve seen Totality a few times, which takes years, going to the edge is a really cool thing to do.”
Photo credit: NASA