Discover Pandipedia
A growing directory of useful answers selected by the Pandi community. Search the collection or browse the latest discoveries.
2277 entries available
Ice can be clear. Why is snow white?
The same frozen water can look like a window or a white blanket. The difference is the route light takes through it.[1][2]
A clear piece of ice has relatively few internal obstacles, so much of the light can pass through. Snow is a collection of ice grains with air between them. At those many boundaries, light changes direction again and again; much of it is scattered back toward your eyes.[3][4]
AI-generated explanatory diagram, not a measured ray-tracing simulation. · Source
Clean snow returns visible light without strongly favouring one colour, so the mixture looks white. Ice containing many bubbles or fractures can look cloudy for a similar reason.[5]
Historical book illustration, AI-assisted colour remaster. · Source
Buckley explored the snow-and-ice puzzle in The Fairy-Land of Science. Her crystal drawings make a good starting point for looking closer, but the modern explanation rests on light scattering at the many ice–air boundaries.[6][7]
Let's look at alternatives:
- Modify the query.
- Start a new thread.
- Remove sources (if manually added).
One glowing tube. Many tiny animals.
That glowing tube is a colony. A pyrosome’s wall contains tiny animals called zooids. Each pumps water and filters food; together they form a drifting, luminous tube. One shape in the sea, many lives inside.
Let's look at alternatives:
- Modify the query.
- Start a new thread.
- Remove sources (if manually added).
This bird’s incubator is a compost heap
1/5
Read slide text
- This bird’s incubator is a compost heap.
The malleefowl builds a nursery from sand and leaves.
- First, gather the fuel.
Leaf litter is buried inside the mound.
- The warmth comes from within.
Rotting leaves release heat. Sunlight helps too.
- The father adjusts the mound.
He moves sand to manage the temperature around the eggs.
- The chick digs its way out.
After hatching, it climbs to the surface and begins life independently.
Let's look at alternatives:
- Modify the query.
- Start a new thread.
- Remove sources (if manually added).
Those blue jewels are eyes
Let's look at alternatives:
- Modify the query.
- Start a new thread.
- Remove sources (if manually added).
A forest that turns with the story
Let's look at alternatives:
- Modify the query.
- Start a new thread.
- Remove sources (if manually added).
Gemini Ten: Photography on the Climb to Agena Eight
Transcript
On July nineteenth, nineteen sixty-six, Gemini Ten was climbing toward Agena Eight. The day before, Michael Collins and John Young had docked with Agena Ten. A trajectory correction had left them with only half their planned fuel at docking, and they repeatedly fired Agena Ten’s engine to match orbits with Agena Eight. Collins’s first planned spacewalk was a stand-up EVA: he remained at the open hatch rather than moving away from the spacecraft. It lasted forty-nine minutes. With a seventy-millimetre camera, he took twenty-two ultraviolet images of the southern Milky Way. As the docked spacecraft entered daylight, he also photographed a coloured plate to test how accurately film recorded colour in space. For the planned second EVA, Collins put on the ELSS chestpack and unstowed an umbilical, a line carrying oxygen, communications, and nitrogen. The nitrogen was stored under pressure in the adapter section and would power the hand-held maneuvering unit, a small device for moving an astronaut with gas thrust. Fuel remained scarce. The crew rendezvoused with Agena Eight about ninety minutes before the planned EVA, shaping the timing of the next spacewalk around the mission’s limited fuel.
Let's look at alternatives:
- Modify the query.
- Start a new thread.
- Remove sources (if manually added).
The creature drilling through this ship is a clam
The name gives you the wrong picture. A naval shipworm, Teredo navalis, is a bivalve: a relative of clams and mussels, with an unusually long body.[1]
Its shell has become a tool. Two small, ridged valves at the buried end grind and tear wood fibres, opening a tunnel through submerged timber. The long body follows inside; siphons near the entrance exchange water with the sea.[2][3]
AI-generated explanatory reconstruction, not a photograph. · Source
A sound-looking plank can hide a maze of burrows. The Ocean World describes ships, piles and sea defences damaged from within, long before the destruction was obvious on the surface.[4]
Let's look at alternatives:
- Modify the query.
- Start a new thread.
- Remove sources (if manually added).
The Marshall study, and what the source does not establish
After November 1964, budget pressure and NASA’s choice to emphasize crewed Earth-orbit missions sharply reduced piloted Mars-study activity. A Marshall Space Flight Center team still examined a Saturn-and-Apollo-based Mars flyby, but it remained a study concept, not a funded direct-landing program or a flown mission.[1][2][3]
| Period | Reported Mars-study activity |
|---|---|
| 17 months before November 1964 | 29 piloted planetary mission studies, costing $3.5 million.[4] |
| November 1964 through May 1966 | Four contracted studies, costing $465,000.[5] |
The change accompanied a policy shift: NASA assigned low priority to developing a new rocket after Saturn and proposed concentrating post-Apollo crewed flight on Earth orbit, using Apollo-developed technology. The later study count and spending show how markedly Mars-related study work contracted during that period.[6][7]
The Marshall study, and what the source does not establish
Separately from the general count of contracted studies, a Marshall team led by Ruppe examined a crewed Mars flyby using Saturn launch vehicles and Apollo hardware. Its February 1965 report judged such flybys technically feasible in the mid-to-late 1970s, using a modified Apollo command and service module, a pressurized hangar, and automated probes.[8]
The source mentions four later studies but does not identify them as contractor studies or describe their architectures. It therefore does not provide enough detail to compare contractor designs with Marshall’s concept. Nor does the feasibility assessment establish an approved, funded direct-landing effort or a mission that flew: it documents a study, not a flight program.[9][10]
Let's look at alternatives:
- Modify the query.
- Start a new thread.
- Remove sources (if manually added).
When flowers ran warm
Let's look at alternatives:
- Modify the query.
- Start a new thread.
- Remove sources (if manually added).
Farmyard Mothers on Guard
Let's look at alternatives:
- Modify the query.
- Start a new thread.
- Remove sources (if manually added).