Every month on Earth Matters, we offer a puzzling satellite image. The September 2025 puzzler is shown above. Your challenge is to use the comments section to tell us where it is, what we are looking at, and why it is interesting.
How to answer. You can use a few words or several paragraphs. You might simply tell us the location, or you can dig deeper and offer details about what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure feature. If you think something is interesting or noteworthy, tell us about it.
The prize. We cannot offer prize money or a trip on the International Space Station, but we can promise you credit and glory. Well, maybe just credit. Within a week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. After we post the answer, we will acknowledge the first person to correctly identify the image at the bottom of this blog post. We also may recognize readers who offer the most interesting tidbits of information. Please include your preferred name or alias with your comment. If you work for or attend an institution that you would like to recognize, please mention that as well.
Recent winners. If you have won the puzzler in the past few months, or if you work in geospatial imaging, please hold your answer for at least a day to give less experienced readers a chance.
Releasing comments. Savvy readers have solved some puzzlers after a few minutes. To give more people a chance, we may wait 24 to 48 hours before posting comments. Good luck!
Taklamakan Desert in Xinjiang Province, China!
The interest may be the presence of a river – rare occurrence?
Photo of an ephemeral stream in the Taklamakan Desert in northwest China. It is located more or less in the center of Asia. China has planted large areas around the edges of the desert in an effort to reclaim land from being desert.
This is the Hotan River on its northward progression across the Taklamakan Desert in Xinjiang, northwestern China as seen in visible imaging approximating the bandwidth of the human eye. It’s notable as an example of a braided river threading an expanse of sand dunes, with the sediment filling the watercourse and creating an ever-changing pattern of channels as the sand is deposited, scoured away, and redeposited. Dark areas along the river are probably vegetation, which only survive thanks to the water in the river and stand in contrast to the sand desert and its virtual absence of plant growth.
The colourful band across the lower portion of the photo is an exposed ridge of sedimentary rocks, probably sandstones, with red and orange hues that indicate the presence of iron oxides and possibly dating the formation to the Devonian era. The abrupt end of the ridge is most likely a feature created by the erosive force of the sand-laden water in the river.
The locality is the central part of the Tarim basin, China, where Palaeozoic sequences buried deep underground are exposed here, due to the structural movement (thrusting).
Image:
White Nile, South Sudan
River changing course.
Its the meeting of the Mazatagh range with the Hotan River a tributary of the Tarim river crossing the Taklamakan desert in West China
Rio Negro?
Nile River.
I think it’s the Kuiseb river flowing through the Namib desert in south central Namibia near the Gobabeb research station?
Taklamakan Çölü ve Hotan Nehri ( 38.452602° 80.866176° )
Taklamakan Çölü ( / ˌ t æ k l ə m ə ˈ k æ n / TAK -lə-mə-KAN );
Çin’in kuzeybatısındaki bir çöldür . Güney Sincan’daki Tarım Havzası içinde yer alır , güneyde Kunlun Dağları , batıda Pamir Dağları , kuzeyde Tanrı Dağları ve doğuda Gobi Çölü ile sınırlıdır.
Hotan Nehri veya Ho-t’ien Nehri, (Çince: 和田河; pinyin: Hétián hé);
Beyaz Yeşim (Yurungkaş) ve Kara Yeşim (Karakaş) nehirlerinin birleşmesi ile oluşur ki kuzey Kunlun Dağlarından kuzey Çindeki Taklamakan Çölüne doğru akar. İki nehir çölün ortasında, ortalama 145 km (90 mil) Hotan şehrinin kuzeyinde birleşir. Nehir sonra 290 kilometre (180 mil) çölün içinden kuzeye doğru akar ve Tarım Nehrine sularını boşaltır. Dağlarda eriyen kar sularıyla beslenen nehir, yaz aylarında tamamen kurur. Tarım Havzasında su ileten tek Hotan nehir yatağıdır.
Saygılarımla
Nile River through desert
this is a satellite image showing the northern boundary of the Issaouane Erg, a large sand sea in the Sahara Desert of Algeria.
Left Side (Yellow/Orange): This is the edge of the Issaouane Erg, a vast field of wind-sculpted sand dunes.
Right Side (Dark River Channel): This is the dry riverbed, or wadi, of Oued Issaouane. It acts as a natural barrier, preventing the sand dunes from advancing further to the east (right).
The Red Line: This prominent feature is an escarpment or cliff face, marking the sharp boundary between the sand sea and the older, underlying rock formations through which the river has carved its path. The reddish color is likely due to the presence of iron oxides in the exposed rock.
The image is famous among geologists and earth scientists for beautifully illustrating the stark contrast between different geological landscapes and processes side-by-side. The approximate coordinates for this location are around 28.7°N, 6.7°E.
a section of the Nile River surrounded by desert sands
Hotan River in Xinjiang Province and in the Tarim Basin. Easy-Peasy.
A sector of the Niger River in the territory of the North African country of Mali (or possibly Niger), where the sand dunes of the Sahara desert transition to the dry landforms of the Sahel.
This photo looks like the Atacama Desert in Chile and the long ribbon reminds me of a dumping ground for used clothes.
Hotan river in taklamakan desert, China.
Photo is of Sarah’s desert
This looks like a paleochannel or wadi cutting across sand‐dominated terrain in a desert region, possibly in North Africa (e.g. Sahara) or the Arabian Peninsula. The contrast between smoother sands and textured ridges suggests migrating dunes meeting more stable ground. The darker line could signify a remnant watercourse, occasional moisture, or vegetation along the channel. It’s interesting because it highlights how water once shaped this landscape, and how wind continues to sculpt it today. Likely captured by Landsat or Sentinel imagery in natural/near-natural color modes
This looks like a paleochannel or wadi cutting across sand‐dominated terrain in a desert region, possibly in North Africa (e.g. Sahara) or the Arabian Peninsula. The contrast between smoother sands and textured ridges suggests migrating dunes meeting more stable ground. The darker line could signify a remnant watercourse, occasional moisture, or vegetation along the channel. It’s interesting because it highlights how water once shaped this landscape, and how wind continues to sculpt it today.
Hotan River, China
38.439784, 80.877103
Judging from the green strip through sandy desert terrain, I would guess that your satellite image shows a length of the Nile River in upper Egypt…but downriver from the Aswan Dam. Looking at the slight bend of the river, perhaps this is in the vicinity of ancient Thebes.
China – Taklamakan Desert – Hotan River. The river seems fuller with more greenery around it indicating more water.
this is this Hotan River draining north from the Kunlun Shan into the Taklamakan desert (Xinjiang, China). how many perennial rivers with actual surface flow cut through a shifting sand (dune) desert!?
Taklamakan Desert
La imagen corresponde a una zona del Rio Nilo en Egipto. es una imagen optica (Landsat8/9, Sentinel2) en combinacion RGB.
It is Hotan River in the Taklamakan, which is part of the Gobi Desert. The dunes form on one side because prevailing winds deposit sand there while the river’s moisture and mountain barrier protect the opposite side.
I believe this photo is located in Moyu County, Hotan Prefecture, Xinjiang Province, China. The center coordinates is 38°35’11.68″N, 80°42’50.43″E. The image width is about 78 kilometers. The satellite that took the photo was Landsat 9. The desert in the picture is the Taklamakan Desert, a temperate desert with the Hotan River flowing through it. The road along the river is National Highway G580.
I believe it is the seasonal Hotan River, Taklamakan Desert, Tarim Basin, China,
at about 38°39’59.1″N, 80°46’34.1″E. – Greetings, Granyia
This is the Hotan river in the Taklamakan desert of China. It’s interesting because the river crosses the desert south to north.
Chi-la-mu-yeh-te-tao well; Khotan river or the Ho-t’ien River
by wiki – Hotan River (China)
Geography: This river originates from the confluence of the White Jade and Karakash Rivers in northern China.
Course: It flows north into the Taklamakan Desert, where it joins the Tarim River.
Characteristics: The river is fed by melting snow, making it a seasonal river that is dry for most of the year.
Historical Significance: The riverbed was once a vital transportation route across the Tarim Basin before the construction of a highway in 1995.
Hello,
I am Abena, a Teaching Assistant at the Department of Geographical Sciences, University of Maryland, College Park. I sending this message on behalf of one of my students, Alsheimer Kurt who attempted to solve the “Image of the Day” for September.
He thinks the Taklamakan Desert River is being highlighted in the image.
Kind regards,
Abena