91色情片

2GA52R4 A woman on the beach at Portrush, Co. Antrim, on Northern Ireland's north coast doing open water swimming in the Atlantic Ocean.

When sea swimming, is it better to enter quickly or to take your time?

The most important consideration when swimming in the sea is safety, say our readers 鈥� but it also depends on how cold the water is

2K6A82T Artist's concept of astronauts and human habitats on Mars.

What is the minimum number of people needed for a Martian settlement?

purebred beagle puppy is learning the world in first time; Shutterstock ID 566398009; purchase_order: -; job: -; client: -; other: -

This week鈥檚 new questions

Two seagulls above aircraft wing

Do winged animals ever suffer comparable mishaps to aircraft?

2R067KD The Great Sphinx is the oldest known monumental sculpture in Egypt. It was built more than 4,500 years ago to guard the pyramid of Khafre at Giza.

How long will it be until the pyramids in Egypt weather away?

B1PP5G Spiral Galaxy M74 i. Image shot 2008. Exact date unknown.

What makes galaxies spin in a certain direction? Part two

GUILIN, CHINA - OCTOBER 16: Juri Hollmann of Germany and Movistar Team leads the peloton during the 4th Gree-Tour of Guangxi 2023, Stage 5 a 209.6km stage from Liuzhou to Guilin / #UCIWT / on October 16, 2023 in Guilin, China. (Photo by Tim de Waele/Getty Images)

This week鈥檚 new questions

Brachycybe lecontii (F Andrognathidae) millipede

Is there a limit to how small an adult arthropod can be? If so, why?

Beautiful sky and blue ocean; Shutterstock ID 122089855; purchase_order: -; job: -; client: -; other: -

Would whisking cold water up from the ocean depths help with warming?

B095JB Swarm of gnats (Nematocera), Bavaria, Germany, Europe

Are gnats attracted to eyeballs, or do we just notice these ones most?

Eye gnats are indeed attracted to lachrymal secretions, or tears, say our readers. They are also fond of animal secretions and open wounds

This week鈥檚 new questions

Why don鈥檛 marine mammals like whales get 鈥榯he bends鈥�?

When was it realised that moonlight is reflected sunlight? Part 2

How do dogs recognise that another animal is also a dog? Part 3