@dw.science 3I/ATLAS — since its discovery in July, some of humanity’s most powerful space telescopes have been tracking it. It’s a mysterious interstellar object currently hurtling through our solar system. It’s expected to reach its closest point to the Sun on October 29th or 30th. Its hyperbolic trajectory reveals something extraordinary: when traced backward, its path clearly shows that it came from outside our solar system. Some have speculated that 3I/ATLAS might be an alien spacecraft, but observations from advanced telescopes suggest a more natural explanation: it’s most likely a comet, with an icy nucleus and a glowing cloud of gas and dust, known as a coma. Still, this deep-space visitor is no ordinary comet. It has some unusual features never seen before: - Its coma contains 8x more carbon dioxide than water - Astronomers have detected nickel, but no iron Based on its speed and trajectory, scientists believe 3I/ATLAS may be the oldest comet ever observed — possibly much older than our Solar System. It will temporarily disappear from view as it passes behind the Sun, but when it reemerges in late November, it will be even more active as the Sun’s intense heat causes its ice to vaporize — giving scientists another chance to study its origin and composition. Author: Naomi Mihara #nightsky #stargazing #Spacenews #dwscience #Astronomy #3iAtlas ♬ Originalton - DW Science

@dw.science Air pollution is a global problem — but in Delhi, winter smog often reaches crisis levels, frequently breaking past ‘very unhealthy’ into ‘hazardous’ territory. The Air Quality Index (AQI) is a system that translates pollution levels into a health-based score. 0-50 Good 51-100 Moderate 101-150 Unhealthy for sensitive groups 151-200 Unhealthy 201-300 Very unhealthy 301+ Hazardous The monitoring stations are designed to detect specific pollutants. Some use lasers to scan the amount of particulate matter in a cubic meter of air, while others use satellite imaging to measure energy reflected or emitted by the Earth. Pollutants that harm your health include particulate matter (PM10 and PM2.5), ozone, carbon monoxide, lead, nitrogen oxides, and sulfur dioxide. Particulate matter is a mix of tiny solid or liquid particles — such as soot, dust, and minerals— that can irritate and inflame the lungs. The smaller the particle, the more dangerous it is. -PM10: Particles up to 10 microns in diameter -PM2.5: Particles just 2.5 microns wide — about 30 times thinner than a human hair Because of their size, PM2.5 particles can penetrate deep into the lungs and even enter the bloodstream. This increases the risk of heart disease, stroke, lung cancer, and chronic respiratory illnesses. If the air in your area turns toxic, follow this advice: Stay indoors during peak pollution hours (morning and evening rush hour periods) Wear a respirator mask such as an N95 mask if you need to go out Use an air purifier at home Check reliable air quality indexes for your country Author: Naomi Mihara Delhi air quality index source: CPCB #pollution #airquality #airqualitytips #India #dwscience ♬ Originalton - DW Science