Rare Snow Falls At The Edge Of The Sahara Desert
"Snow fell on the edge of northwest Africa’s Sahara Desert in mid-December 2016, a rarity for the area. The Landsat 7 satellite’s Enhanced Thematic Mapper Plus (ETM+) sensor captured the left image of white over a caramel-colored landscape southwest of the Algerian community Ain Sefra, a town sometimes referred to as the gateway to the desert. All of the snow disappeared except at the highest elevations, as shown in the right image captured by Landsat 8. Ain Sefra’s last snowfall occurred in February 1979."
yep....noticed that too.
Um, no I didn't notice that at all. One effort shows data from 2004, mainly due to 2004 being such a major year for the Muir Glacier. The rest are pretty recent. 20% are from 2020. 75% from the last 5 years.
Unless you meant that any remote sensing data is from the past, even if taken seconds ago.
Satellite data usually takes a little while to be made public due to processing requirements (e.g. ICESat-2 was launched in 2018, but some higher level products haven't been produced yet.) Then researchers need time to figure out what the data is actually showing.
Also, regarding the images being a few years old, that’s obviously for security reasons. Satellite images made available to the public are never current for obvious reasons.