A pair of Iridium satellites flaring. Jupiter is to the right and the bright star Arcturus is to the lower left. |
Iridium
Flares
Understanding Iridium Flares
Our night skies are packed full of stars and
planets to observe on a dark night.
However,
there are more objects closer to home that you
can plan on seeing every so often.
These
include the International Space Station (ISS) and numerous satellites.
The ISS
appears as a slow-moving high-altitude craft during its crossings, while most
satellites look like dimmer points of light moving against the backdrop of
stars.
Some satellites appear to move east to west, while others are in polar orbits
(moving nearly north-south).
There are thousands of artificial satellites around
Earth, in addition to thousands of other objects such as rockets, reactor
cores, and pieces of space debris (sometimes referred to as “space junk”).
Not all of
them can be seen with the naked eye.
There's a
whole collection of objects called Iridium satellites that can look very
bright during certain times of day and night.
Glints of
sunlight bouncing from them are referred to as "iridium flares" and
they can be observed fairly easily if you know when and where to look during
the satellite orbits.
Many
people probably have seen an iridium flare and simply not
known what they were looking at.
It also
turns out that other satellites can show these glints, although most are not as
bright as the iridium flares.
WHAT'S IRIDIUM?
If you use a satellite phone or pager,
chances are the signals you receive or send come through the Iridium satellite
constellation, a set of 66 orbiting stations that provide global
telecommunications coverage.
They follow highly inclined orbits, which
means that their paths around the planet are close to (but not quite) from pole
to pole.
Their
orbits are roughly 100 minutes long and each satellite can link to three others
in the constellation.
The
first Iridium satellites
were planned to be launched as a set of 77.
The name "Iridium" comes from the element iridium, which is number 77
in the periodic table of the elements.
It
turns out that 77 were not needed.
Today,
the constellation is used largely by the military, as well as other clients in
the airline and air traffic control communities.
Each Iridium satellite
has a spacecraft bus, solar panels, and a set of antennae.
They
go around Earth in roughly 100-minute orbits at a speed of 27,000 kilometers
per hour.
THE HISTORY OF IRIDIUM SATELLITES
Satellites have been orbiting Earth since the
late 1950's when Sputnik 1 was launched.
It soon
became obvious that having telecommunication stations in low-Earth orbit would
make long-distance communications much easier and so countries began launching
their own satellites in the 1960's.
Eventually,
companies got involved, including the Iridium Communications Corporation.
Its
founders came up with the idea of a constellation of stations in orbit in the
1990's.
After the
company struggled to find customers and eventually went bankrupt, the
constellation is still in operation today and its current owners are planning a
new "generation" of satellites to replacing the aging fleet.
Some of
the new satellites, called "Iridium NEXT", have already been launched
aboard SpaceX rockets.
This new generation of Iridium sats will no
doubt enable more flare-watching among Earth-based observers.
WHAT IS AN IRIDIUM FLARE?
As each Iridium satellite orbits the planet, it
has a chance to reflect sunlight toward Earth from its triad of antennae.
That flash
of light as seen from Earth is called an "Iridium flare".
It looks
very much like a meteor flashing through the air very rapidly.
These
brilliant events can happen up to four times a night and can get as bright as
-8 magnitude.
At that
brightness, they can be spotted in the daytime, although it's much easier to
see them at night or in twilight.
Observers
can often spot the satellites themselves crossing the sky, just as they would
any other satellite.
LOOKING FOR AN IRIDIUM FLARE
It turns out that Iridium flares can be
predicted.
This is
because the satellite orbits are well known.
The best way to find out when to see one to
use a site called Heavens Above, which keeps track of many known bright
satellites, including the Iridium constellation.
Simply
enter your location and get a feel for when you might see a flare and where to
look for it in the sky.
The
website will give the time, brightness, location in the sky, and length of the
flare.
CLICK
HERE . . .
CLICK
HERE . . .
CLICK
HERE . . .
CLICK
HERE . . .
CLICK
HERE . . .
. .
Multi-Media Filter, Highly-Activated Carbon Filter,
Zeolite-Process Water Softener With Brine Tank,
Fiberglass Ballast-Type Pressure Tank
(fully automatic backwash & regeneration)
|
PURICARE
Water
Treatment
Systems
.
.
...
Aganan, Pavia, Iloilo, Philippines
...
CLICK HERE . . . to view company profile . . .
CLICK HERE . . . to view company profile . . .
No comments:
Post a Comment