A huge number of satellites revolve around our planet. Each of them has its own purpose. The Iridium satellite series revolves around the Earth to transmit data and voice. This equipment is covered with a smooth surface and is able to reflect the sun's rays, which our eyes perceive as quick glare. Outbreaks of Iridium are a fairly common occurrence that can be observed by every inhabitant of our planet. Sometimes, this phenomenon is confused with a shooting star, with a UFO flight, and even with a visible satellite, but these are erroneous opinions. How to see such a glare and how to find out when it will be and where exactly to look? Let's figure it out.
So different satellites
Before we calculate the time of the appearance of the next outbreak of Iridium, we recall what satellites are and what they are. So, a satellite (ISS) is an artificially created aircraft that revolves around the Earth. The height and speed of this space equipment depends on its purpose and technical characteristics. There are: communication satellites, astronomical, biosatellites, space stations and ships, meteorological satellites and experimental.
Communications spacecraft are typically located in low reference orbit. For example, the Iridium satellite, whose flares we can see, moves in low orbits with an inclination of 86 ° and a height of 780 km. This allows him to receive signals from stations located on Earth, amplify them and radiate back. The Iridium series of satellites includes 66 spacecraft, the service area of which covers the entire Earth. Initially, it was planned to create 77 satellites. This number is the atomic number of Iridium, that's where the name of the company came from, and although the spacecraft were launched 11 less, the name remained.
Beautiful phenomenon
Outbreaks of Iridium are a very beautiful phenomenon lasting about 10 seconds. The position and movement of each aircraft is clearly fixed by the system, which means that the appearance of glare can be easily counted and seen. This is one of the most striking celestial phenomena resembling the appearance of a shooting star. Of course, not all flashes of Iridium are equally clearly visible, because the satellites are in constant motion and the reflection angle may be too small, which means that the phenomenon itself will be almost invisible. In addition, clouds, fog, precipitation, and strong winds may interfere with seeing this phenomenon.
How does an outbreak occur?
If you enable slow motion shooting of this phenomenon, you can see how a point lights up in the sky, starting a movement, it gains maximum brightness and then goes out. The reflection of these rays can be 2 times brighter than that of the planet Venus. In astronomy, the Vega star is considered the standard of zero magnitude for the brightness of a celestial body. All that is brighter than it is negative numbers, which are paler - positive. The most visible outbreaks of Iridium are from -6 to -9.5 m. For example, for the Sun this value is -26.7 m, for the Moon -12.74 m, for Venus -4.67 m.
Glare is reflected not even by the satellite itself, but by its antenna, almost two meters long, located at an angle of 40 ° from the axis of the spacecraft. It is silver plated for thermal control. The very axis of the satellite’s body is supported vertically with respect to the Earth’s surface, and this allows us to see the Iridium flashes. The photos below prove the fact that this phenomenon is similar to a shooting bright star. An example of such glare is the usual mirror: when a ray of the sun hits its surface, we see its reflection on the wall, popularly called the “sun bunny”.
How to calculate flash time
As mentioned earlier, the location of each Iridium satellite is known very accurately. This allows the calculation method to calculate the time of occurrence of such outbreaks. Of course, for astronomers and scientists to calculate the time and place of the appearance of glare is not difficult, but for the rest a huge amount of mathematical calculations can be a difficult task. There are various programs and sites that calculate the time it takes for flashes to occur in seconds. There are also special applications on the phone, for example, the Iridium program. This utility is convenient in that the phone, including the camera, also shows the location of the flash. One of the best sites is Heavens-above. It automatically calculates the time of occurrence of the Iridium flash and its exact coordinates. The resource even displays information about which satellite gives glare.
Choose a location
After you have visited the site, you must indicate your location. To do this, in the context menu there is a section "Configure location". At this stage, you must accurately select the city, street and even the house from which the observation will be carried out. If the entered data is not accurate, you most likely will not see the flash. In addition, you need to check the time zone, as well as the clock in the phone, because the flash time matters. After all parameters have been entered and saved, a rectangular frame with the entered data will be displayed in the upper right corner. It will indicate the location (latitude and longitude), time and time zone. If the frame displays all the data correctly, then you can proceed to the next step.
We calculate time
In order to see when the next event will be, it is necessary to go to the "Iridium outbreaks" section in the main menu. The schedule of glare data is indicated here. At the very top, you can select the search interval, as well as enable the option "daytime flash". If the reflection is bright (from -7 to -9), then it can be seen even in the afternoon. In the table presented on the website, the following are important for us: brightness (first column), altitude and azimuth. These data are necessary in order to know at what point in the sky to wait for a flash. So, from the table, select the brightness according to the highest digit (more than 6.5) with a negative sign. Next, look at the date of this outbreak and click on it. The new page shows all the detailed information for a specific number.
Where to watch the flash - navigate in the sky
To begin with, we will determine the side in which we will wait for the highlight from Iridium. Azimuth is the angle between the point we need and the north. If the azimuth is 0 or 360 °, then the flash will occur strictly in the direction of the north, if 180 ° means in the south, 90 ° in the east and so on. In order to accurately navigate, you need to take a compass. If there is no such device nearby, then the line along which the flash will pass is clearly visible on the map - you can navigate along it.
We need a height angle in order to determine in what place in the sky a flash will occur. An exact protractor will be required for accurate determination. Since the appearance time is known in seconds, you can go out a little earlier, so you definitely won’t miss outbreaks of Iridium. Not everyone knows what this phenomenon is, which means that you can surprise friends and acquaintances by saying that here and now a star will fall for them.