Artificial Earth satellites and features of observing them - Part 2. How to see the ISS with the naked eye Why satellites glow at night
Interesting to a recent post:
when I was watching the eclipse, I also saw a bright object flying high from west to east, quite bright compared to stars. revised the approximate time, magnitude and direction according to the Stellarium program. it turned out that it was the ISS)
I have always been surprised by statements that the ISS and other satellites declared by officials are visible from Earth with the naked eye. Let's try to figure it out.
The ISS orbit is declared at an altitude of 408 km.
Max. The dimensions of the station are stated to be 109 meters (including deployed batteries). This is approximately 4 carriages of a passenger train or 7 trucks (20-ton, Euro-trucks).
And as far as I know, the ISS is the largest orbital object (of our civilization).
Now remember the view from the airplane window during the flight.
Do you remember? Were the trucks or trains below clearly visible?
And this is only 10 km altitude...
To check, consider this thing:
Here are 2 islands on Lake Chapala in Mexico.
I chose them for two reasons:
1. On the surface of the water, the island is better visible than any other artifact on the ground, which is all built up and objects are mixed into mush at a distance (you can, of course, look for solar panel farms in the desert for maximum clarity, but you’re too lazy. If you find it, please let us know)
2. One of the islands is clearly visible from a height; it can be used as a landmark
We pay attention to the small island. Its dimensions are 2.5 times larger than the ISS (~260 by 100 m) and it is clearly visible from a height of 5.44 km, like the large one nearby:
And now we rise to an altitude of 400 km:
Do you see such a small dot there right between the tip of the arrow and the letter P?
This big the island and it is barely visible. The little one disappeared completely.
I watched it on regular Google Earth with a screen resolution of 1920x1080. You can try it yourself.
It is clear that the ISS and its mirror arrays can reflect, but is this light enough to be visible from Earth?
Other satellites, as far as I know, do not at all exceed the size of machines with orbits of at least 200 km, and this is for spy vehicles, which obviously will not be entered into civilian databases.
If such arguments seem insufficient to you, remember that 400 km is the distance from Moscow to Nizhny Novgorod.
And try to see not even a single building, but the entire city from such a distance)
Or just look at the Earth in reverse order, preferably in full screen:
Earth from space in 4k. ISS flights over the continents of the Earth, the latest images. VITA mission. ESA 2018
At the 1:45 mark, Geneva's Lake Leman is visible.
The arrow marks the Geneva Cointrin airport; against the general background of the city, it can also be used as a landmark:
This is what it looks like in full screen with 4K video quality:
The length of the runway is ~4 km, the width including the lawns is ~400 m, but even it is almost invisible from a height of 400 km!
So is it possible to see the ISS from this distance, do you think?
And bonus questions from our quiz:
Who or what is taking all these masterpiece pictures of the ISS from a couple of hundred meters, a quadcopter, a satellite, a kamikaze paparazzi?
Why don't you ever see the stars in them unless it's obviously photoshopped CGI?
ALL videos of the astronauts going into space were filmed from on board, THERE IS NOT A SINGLE VIDEO filmed from the side, only graphics! Can you explain this?
And why not record the eclipses that are so interesting to everyone on the ISS cameras, since NASA and other agencies constantly broadcast them from Earth? ;)
UPD from comments:
This is what the ISS altitude of 400 km looks like compared to the planet.
What lights it up from below, the city lights? because the sun can only do this for a VERY short period
Is it possible from this height to see such a refraction of the surface, as they show us, i.e. almost a quarter of the planet, and sometimes more?
As part of the review of the features of monitoring artificial Earth satellites, in the previous article we focused on a review of the advanced artificial Earth satellite - the ISS; in the previous article we focused on a review of the advanced artificial Earth satellite - the ISS - the International Space Station, we learned how to observe the flight of the ISS.
The main thing that is needed to observe artificial satellites is good vision and a forecast indicating their passage over various points on the planet. Of course, with the help of binoculars or a telescope you can see details and objects that are inaccessible to the naked eye. With 7x50 binoculars (that is, binoculars with 50mm lenses that provide 7x magnification), it is already possible to observe objects of magnitude 8 to 9 in a still atmosphere in a very dark sky.
Owners of a telescope with a diameter of 114 mm can even access artificial satellites of magnitude 10-11, that is, much lower brightness. With some experience, you can learn to “follow” the satellite manually, but everything becomes easier when using a clock motor connected to a computer where the satellite coordinates are entered. There are wonderful programs on the market that provide data on hundreds of low-orbit artificial satellites; Thanks to these programs, the telescope's clock motor easily follows them automatically.
How many artificial satellites are available for observation?
Regardless of the observation location, hundreds of artificial satellites are located above the horizon at any hour of the day. However, only a few dozen are easily observed under favorable lighting conditions.
Russian Soyuz spacecraft (or their cargo version, Progress) are also among the man-made objects potentially observable from Earth. "Soyuz" and "Progress" under favorable lighting conditions reach magnitude 1, and under normal conditions exceed magnitude 3. Thus, they are visible to the naked eye, although only as luminous points. To get some details, you can first check the Soyuz visibility conditions in the days immediately after launch, and then use your telescope.
Typically, one or two objects can be seen with the naked eye every half hour; when using a telescope like yours, their number increases to 10. The brightest artificial satellites are listed on the website n2yo.com/satellites/7cH. This site contains mostly technical information in English, but with some experience you can find the most important information and navigate through the data regarding different satellites.
About photogenicity. Like other celestial objects, artificial satellites can be photographed through a telescope. Some astronomy enthusiasts, for example, have excellent photographs of the Mir station, taken before its death in the atmosphere, and the International Space Station. In these photographs you can even see various station laboratories.
And there is “garbage” too. Using the telescope, you can see over 10,000 objects of space debris flying in low Earth orbit. Typically, these are parts of the rockets used to launch a satellite or space station that remain in orbit after use. There are also fragments of exploded rockets or decommissioned satellites. Calculating the orbits of these objects and their locations is very difficult. However, major space agencies have this information and use it to avoid collisions with active satellites or the International Space Station.
What and how can you see while searching for satellites?
Typically, an artificial satellite appears in the sky as a slowly moving star. This rule, however, has many exceptions. Some artificial satellites, for example, change their brightness just as they pass over the observation point. This is usually caused by changes in lighting conditions, sometimes producing very spectacular effects. Again, everything depends on the height of the satellite above the Earth, on its size and on the characteristics of its surface (in particular, reflectivity).
Distance. The brightest satellites visible to the naked eye are often also the fastest moving, since they are in low orbits and, therefore, located closer to the observer. In contrast, observing much more distant geostationary satellites almost always requires a telescope. While passing through the sky, most of the satellites change their brightness by more than one magnitude (with the exception of the Iridium satellites), but some of them can disappear completely, falling into the cone of the earth's shadow, and then appear again. The distance from the satellite to the observer is called "range" and is measured in kilometers or miles. Typically, the higher the range value, the fainter the satellite is visible. The range depends on the height of the orbit above the Earth, as well as on its inclination to the Earth's horizon. A satellite with a very high orbit passing through the zenith (then above the observer's head) may have less range than a satellite in a lower but more inclined orbit that brought it low above the horizon, in which case the satellite in a higher orbit will be brighter than the satellite located at a lower altitude.
The determining factor for the brightness of a satellite is its size. The larger the satellite, the brighter it shines because the larger the surface that can reflect sunlight. This surface is designated by the term "Radar Cross Section".
Surface characteristics. Artificial with traveler with a highly reflective surface will obviously appear brighter. Over time, its surface will become cloudy, and this satellite will change its brightness value, perhaps even by one magnitude. On the contrary, a weakly reflective surface, when destroyed, can become brighter and reflect light better. Another important parameter is the presence of some functional parts of the satellite, such as solar panels or cylindrical antennas, often acting as mirrors. These add-ons can cause a "flash" effect lasting several seconds (sometimes predictable in advance), dramatically increasing the brightness of an object by several magnitudes.
The final factor to keep in mind when determining the brightness of an artificial satellite is the angle of incidence of the sun's rays. As with the Moon, they can illuminate an object more or less directly and completely.
Flash in space. In 1997, the first Iridium series satellites, designed for a new type of cellular communication. It was originally planned that there would be 77 of them, which explains the name Iridium (a chemical element with atomic number 77). But as a result, 95 were launched, of which 72 are still in operation. Satellites placed in polar orbits were supposed to guarantee communication from anywhere in the world to any point on the planet. Today there are tens of thousands of subscribers to this network, but this service has not achieved the planned success.
Super antennas. The dimensions of the Iridium series satellites are relatively small. They reach 4 m in length and, in addition to solar panels, have three main antennas 188 cm long and 86 cm wide. These antennas have excellent reflectivity. It is they who give the Iridium satellites a unique characteristic that makes it possible to distinguish these satellites into a special category that attracts thousands of lovers of astronomical observations. The fact is that they appear in the sky at a relatively low brightness, but, unlike other satellites, within a few seconds they can briefly become 50 or more times brighter than Venus. They then fade back to normal brightness at the same rate at which they were previously so bright.
Iridiums are the only ones artificial satellites, which can be observed during the day. It's not very easy, but if the sky is clear of clouds and bright blue, flares of at least magnitude -6 can sometimes be seen. To find them in the daytime sky, you need to know exactly the points at which these flares should appear.
Heavenly sparkle. The characteristic sparkle of Iridium is easily explained: to fulfill the technical task, these satellites are located in space in such a way that most often one of the antennas reflects the sun's rays directly to the Earth, and this causes a bright flash.
Such flares can be calculated in advance with absolute accuracy and are therefore not difficult to observe from Earth. It is only important to know the exact coordinates of the observation point: a difference of several kilometers is enough for the brightness to change by several magnitudes. The brightest flares reach values of up to -8 and are observable from an area of several square kilometers. Going from brightness +6 (at the limit of naked eye visibility) to -8 means the object increases in brightness by a factor of 400,000.
© Build your telescope No. 20, 2015
Many users would like to enjoy satellite photos of their native places, to see their house, a nearby river or forest from above, in a word, everything that is commonly called “small Motherland”. A tool for realizing this desire can be satellite mapping services, which provide a unique opportunity to view all required geolocations in detailed graphic mode. After my attempts to look at my home online from a satellite, I found really high-quality services and in this article I will share my experiences.
There is a huge variety of mapping services on the Internet that provide the user with access to high-resolution satellite maps. At the same time, the vast majority of such services use the API from Google Maps, and only a few services (including the domestic Yandex.Maps) can boast of their own cartographic developments that differ from the dominant Google maps in this segment.
At the same time, working with such cards is quite formulaic. You go to one of them, turn on satellite display if necessary, and then enter your address (town, street, house number) into the search bar. After this, the service finds the required location, and you can use the mouse wheel to increase or decrease the existing display. If for some reason the service does not find your house, I recommend entering the name of the city (town, village) and street, and then find the desired house yourself using the mouse.
At the same time, some services allow you not only to see your house from above, but also to walk along the streets of your hometown and enjoy the view of the buildings we need up close.
Let's move on to the list of services that will help us see our home from satellite.
Google Maps - look at your home from satellite in real time
The most popular global mapping resource is undoubtedly Google Maps. In addition to maps presented in schematic and satellite form, the service also includes the ability to 360° view the streets of many cities around the world (Street View). Information about street traffic and traffic jams (Google Traffic), a route planner from point A to point B, 3D display of many geographical points, and other useful features.
There are two main options to view your home:
Yandex.Maps - will allow you to see the necessary object in Russia
Another mapping service with which you can enjoy the view of your home is Yandex.Maps. This service is the most popular in Russia, since the level of display of the territory of Russia and the frequency of updating data for the Russian Federation exceeds all existing analogues, including generally accepted maps from Google.
Like the Google Maps service, Yandex.Maps can boast of both standard and satellite display of maps (as well as the “Hybrid” mode, which involves applying various text and schematic markings on a satellite map). In addition, users have access to a street display mode (“Yandex.Panoramas”), a traffic congestion indicator (“Yandex.Traffic”), as well as the crowdsourcing system “People’s Map,” which can be edited by any user.
To view your home using Yandex.Maps, go to the resource, enter your address in the search bar at the top, and press enter. To switch to street view mode, click on the button with binoculars at the bottom of the screen (street panoramas and photographs). And then select one of the streets marked in blue (you will switch to the street view mode at this point, and you will be able to enjoy the color of these places).
Bing.Maps – satellite map from Microsoft
Bing.Maps is an online mapping service from Microsoft, formerly known as Windows Live Maps and MSN Virtual Earth. Its capabilities include satellite display of maps, street view, 3D display for 60 cities around the world, plotting the optimal route and other features that are standard for services of this type.
To watch your home using Bing.Maps, go to the specified service, click on “Road” on the right, and select “Hybrid View”. Then enter the address you need into the search bar and view the view that opens.
MapQuest is a popular American mapping service
"MapQuest" (translated as “Card Search”) is a free American mapping service, the second most popular in the United States after Google Maps. The resource boasts a high degree of detail on the streets of many countries around the world, will help you plot a convenient route, inform you about existing traffic, and much more.
To work with it, you need to go to this resource, click on the button with the image of the globe on the right (Satelite), which will allow you to switch to satellite display mode. After that, in the search bar on the left, enter the address you need (preferably in Latin), and enjoy displaying the desired location using the MapQuest service.
MapQuest is the second most popular service in the United States Conclusion
You can view your home from satellite using the services I listed in this material. For the territory of Russia, I would recommend the Yandex.Maps service - the level of detail and frequency of updated data inspires us to consider maps from Yandex the best mapping service in the Russian Federation. On a global scale, the Google Maps service is the undisputed leader, so it would be optimal to use the tools of this service to display maps of many countries around the world.
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It’s easier to see the sun during the day, but you shouldn’t look at it directly - you can seriously damage your eyes. During eclipses, the danger increases many times over. However, it is also easy to protect yourself from this - with special light filters or by observing the projection.
The moon is also by no means a rare guest in the daytime sky; it appears with different frequencies and brightness depending on its own phases. The easiest time to find it is during the new moon.
Venus, also called the "morning star" and "evening star", reflects the light of the Sun so well that it is relatively easy to see during the day, especially if you know its location. It appears as a tiny flashing white dot.
Satellites. At night, the satellites appear as "moving stars" and require attention and patience to see them. But during the day you can also notice at least one type of satellite - Iridium. Their antennas periodically reflect light so brightly that the effect is called “Iridium flares” and is noticeable even in the daytime sky.
Jupiter is extremely difficult to see in the daytime sky. Requires keen vision and excellent atmospheric conditions. The best time to observe is when Jupiter is at 90 degrees from the Sun during the Moon's first and last quarters.
Mars. If Jupiter is difficult to see during the day, Mars is almost impossible. But it’s “almost” - under rare conditions similar to those observed when observing Jupiter, the red planet can be seen in the daytime sky.
You can actually see the stars during the day during a solar eclipse, although this is a dishonest move. Nevertheless, such observations had important historical significance, at one time confirming Einstein's theories of relativity. With perfect vision and incredible luck, you can see the brightest stars like Sirius in the daytime sky, but it is better to use a telescope.
Comets flying close to the Earth are easy to see in the daytime - the main thing is to wait for the right moment. For example, 2007's Comet McNaught was clearly visible during the day, as was Halley's Comet in 1910.
Meteors are rare and unpredictable, but the brightest ones are clearly visible in the daytime sky. They are even filmed, as in one of the most famous sightings in the United States in 1972.
Supernova explosions can be seen from Earth with the naked eye at irregular intervals from 20 to 300 years. The last evidence of such a phenomenon being observed during the day dates back to 1572. The first candidate for a new explosion is the star Betelgeuse. Of course, its supernova will be visible during the day, but whether the explosion will occur tomorrow or thousands of years later is unknown.
Of course, the Sun is at the top of this list as the most obvious candidate, but the rest of the objects may surprise. For some you will have to strain your eyes or use binoculars, for others you will have to wait for the right moment. What bodies from space are visible on Earth during the day?
Many artificial Earth satellites (hereinafter referred to as AESs) are bright enough to be observed with the naked eye. Moreover, the brightness of the same satellite during its flight can vary from barely noticeable to exceeding the brightness of the brightest star. An example of this is the Iridium communications satellite, during the flight of which flares are observed that are brighter than the light of the full Moon. These changes in brightness are associated with the complex shape of the satellites themselves and with their rotation during flight. Different satellite elements have different reflectivity and area. Reflectors of directional antennas reflect light particularly well, as do heat shields. Solar panels and painted parts of the satellite body are less capable of reflecting light. Naturally, a spherical satellite does not create brightness changes or flashes during its passage.
