North Hawaii News Articles from CFHT
Last Chance to see Iridium Flashes
For the past few years, one of the most dramatic shows in the sky has
been a human creation. In recent weeks, the source of this celestial
display has been making headlines in the financial news: the Iridium
Iridium was an exciting idea which some claimed was the way of the
future, and others feared would be a business disaster. Now it seems
the pessimists were right. The idea was to provide true global mobile
telephone service by creating a network of satellites in low orbits.
These satellites would act like cellphone stations and provide service
to people with special portable phones, anywhere on the planet. Any
single satellite would only be visible for a short time from a specific
point on the ground. The satellites would pass calls along to the next
visible satellite, just as a cellphone station does when you drive from
one zone to the next. To ensure global coverage, Iridium needed a
constellation of 66 satellites.
This was clearly a big, bold project, and it needed big, bold amounts
of money. One of the primary investors was Motorola. This was the
first time that a large number of satellites were mass produced on
anything like this scale. In the past, most satellites have been
custom designed, each one starting nearly from scratch. The simple
fact that Iridium managed to build and launch 66 satellites was a major
achievement. They also managed to keep the cost per satellite quite
low, compared with the typical high cost of satellite development,
construction and launch. Nonetheless, the total cost has been
estimated at between 5 and 7 billion dollars.
Iridium successfully launched their constellation of satellites by
November 1998, only a bit later than planned. Service started soon
after that. Difficulties started to crop up early on: although the
cost per satellite was relatively low, it still exceeded the goal.
During launch, a few satellites failed and had to be replaced. But
these are the sort of setbacks a new company attempting something
daring expects to encounter. The real problem was that not enough
people were buying their product.
From the beginning, Iridium expected to sell the service to
world-traveling business executives. However, in the years between
concept and deployment, ground-based mobile phones became widely
available in cities throughout the world. Given with the weight of
the Iridium phones and the high expense ($3000 to sign on, $7 per
minute), Iridium could not compete. This year, on March 18, after
months of trying to find additional cash from a new investors, Iridium
declared bankruptcy and stopped service. Over the next two years,
they plan to send the satellites into the atmosphere, burning them up.
The 5 billion dollar investment will literally go up in smoke.
The demise of Iridium will mean the end of the phenomenon of "Iridium
flashes". It turns out that the Iridium satellites are unusual in
having a very large, very smooth pair of flat metal plates which act
as antennae. When one of these antennae is pointed in just the right
direction, it reflects the light from the Sun to the Earth's surface.
From the ground, you can easily see the flash of light with your eyes.
In fact, the flashes can be much brighter than Jupiter and last for 10
or 20 seconds. They can even be seen in the daytime!
Since the satellite orbits are very well known, it is actually quite
easy to predict when a flash can be seen from a given spot on the
Earth, and several web sites provide this information. One
particularly good web site along these lines is
On this web site, you can specify your location, either by giving
longitude and latitude, or by selecting your town from a list. Not
only is Waimea included, so are Kawaihae and Honokaa! That is quite
impressive, considering the web site is based in Germany.
A specific flash can be seen from only a very small area on the
ground. At the best location, the flash can be roughly 100 times
brighter than Jupiter is currently; moving only 10 miles away, the
flash fades to the brightness of Jupiter. The center of the flash
generally moves from South to North. I have compiled a list for
readers of upcoming flashes in April. The list also notes if the
flash is best seen from the west side of the Big Island (centered on
Kawaihae), the central areas (centered on Waimea), or the east side
(centered on Honoka'a).
To view one of these flashes, it is best to be ready a few minutes
ahead of the time given. Face the compass direction listed for the
flash (N, SW, etc) and the flash should be visible above the horizon
at the angle given. Remember: 90 degrees means straight up, 45
degrees means halfway up.
The Heavens Above web pages, as well as many others, also tell when
and where you can spot a large number of other satellites. No other
satellites are as bright as the Iridium flashes. Even so, some are
bright enough that they are easily visible in the early evening (or
early morning for the early risers). These satellites can be seen as
bright stars moving slowly across the sky. In particular, with one
click you can get a list of all of the times when Mir or the new
International Space Station can be seen. These are two of the
brightest satellites since they are both so large. So, head outside
and try your hand at "artificial astronomy".
Iridium Flashes for April visible from North Hawaii
| Date || Time || best seen from || altitude || direction |
| April 02 || 08:08:54 pm || Kawaihae bright || 25 deg || N |
| April 03 || 08:02:39 pm || Honoka'a bright || 27 deg || N |
| April 09 || 07:34:46 pm || Kawaihae bright || 35 deg || N |
| April 10 || 07:28:31 pm || Waimea weak || 37 deg || N |
| April 13 || 08:09:07 pm || Waimea bright || 47 deg || SE |
| April 14 || 08:03:08 pm || Honoka'a weak || 47 deg || ESE |
| April 16 || 07:00:58 pm || Kawaihae medium || 42 deg || NNW |
| April 17 || 06:54:41 pm || Waimea bright || 44 deg || N |
| April 18 || 07:47:41 pm || Kawaihae medium || 57 deg || SE |
| April 19 || 07:41:27 pm || Waimea bright || 57 deg || SE |
| April 20 || 07:35:35 pm || Honoka'a medium || 56 deg || SE |
| April 25 || 07:14:09 pm || Kawaihae medium || 67 deg || SE |
| April 26 || 07:07:50 pm || Waimea medium || 67 deg || SE |