Photos of Earth taken by NASA 54 years apart.

Photos of Earth taken by NASA 54 years apart.

It's remarkable that we're alive to witness both. That we get to see our planet the way only a handful of humans ever have 

 Captured over half a century apart, these two "Blue Marble" images represent the bookends of a legacy. On the top is the original Apollo 17 photograph from December 7, 1972, famously taken as the last humans to walk on the Moon left Earth behind. Below it is a stunning new perspective from the Artemis II mission, captured on April 3, 2026, as the first crewed lunar mission of the 21st century began its journey to the Moon.

The 1972 Legacy: Apollo 17

The original "Blue Marble" was captured by the crew of Apollo 17—Eugene Cernan, Ronald Evans, and Harrison Schmitt—from a distance of about 18,000 miles (29,000 km

• A Unique View: Because the Sun was directly behind the spacecraft, the Earth appeared fully illuminated, like a glass marble.
• Visible Landmarks: This iconic shot clearly shows the coastline of Africa, the Arabian Peninsula, Madagascar, and the south polar ice cap.
• Cultural Impact: It became one of the most widely distributed images in history, serving as a powerful symbol for the burgeoning environmental movement.

The 2026 Return: Artemis II

The 2026 image marks a historic "full circle" moment. Launched on April 1, 2026, Artemis II carried the first four humans—Commander Reid Wiseman, Pilot Victor Glover, and Mission Specialists Christina Koch and Jeremy Hansen—beyond low Earth orbit in over 50 years.

• The "Hello World" Shot: This new view was captured by Commander Reid Wiseman through an Orion spacecraft window after the critical translunar injection (TLI) burn.
• Technological Evolution: While the 1972 photo was shot on film using a Hasselblad camera, the 2026 image was captured digitally using a Nikon D5.
• A New Perspective: Captured roughly 100,000 miles from home, the image reveals a vibrant globe with visible auroras along the edges

Comparing the Missions

While both missions share the goal of lunar exploration, their objectives differ significantly:

Feature	Apollo 17 (1972)	Artemis II (2026)
Mission Type	Lunar Landing	Lunar Flyby
Crew Size	3 Astronauts	4 Astronauts
Max Distance	~248,655 miles	~252,757 miles (new record)
Spacecraft	Apollo Command/Lunar Modules	Orion Capsule ("Integrity")
Launch Vehicle	Saturn V	Space Launch System (SLS)

Artemis II is not just a repeat of history; it is a critical test flight. By verifying Orion's life-support and navigation systems, this 10-day mission paves the way for Artemis IV, which aims to return humans to the lunar surface in 2028. 

What animal does this eye belongs to?

 What animal does this eye belongs to?

The Anatomy of the Bovine Eye

1. The Horizontal Pupil

Unlike humans, who have round pupils, or cats, who have vertical slits, cows have horizontal, rectangular-shaped pupils.

• Panoramic Vision: This shape allows for a wide, panoramic view of the horizon. Cows have a field of vision of nearly 330 degrees, meaning they can see almost everything around them except for a small blind spot directly behind their heads.
• Ground Focus: The horizontal orientation helps them keep the ground in sharp focus while grazing, allowing them to spot potential predators approaching from a distance.

2. The Nigra Corpora (Granula Iridica)

If you look closely at the top edge of the pupil in the image, you might notice small, dark, cloud-like structures. These are called nigra corpora.

• Natural Sunglasses: These structures act like built-in sunshades. Because cows spend most of their time in open fields under direct sunlight, the nigra corpora help shade the pupil and reduce glare, preventing "snow blindness" and protecting their sensitive retinas.

3. The Tapetum Lucidum

While not directly visible in the photo without a flash, cows have a reflective layer behind their retina called the tapetum lucidum.

• Night Vision: This is what causes a cow’s eyes to "glow" when hit by a car's headlights or a flashlight. It reflects light back through the retina, significantly improving their ability to see in low-light conditions.

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Sensory Experience: How a Cow Sees the World

• Color Vision: Contrary to the myth that bulls only see red (they are actually "color blind" to red), cows are dichromatic. They see the world primarily in shades of blue and yellow. They struggle to distinguish between reds and greens, which appear as yellowish-gray to them.
• Depth Perception: Because their eyes are on the sides of their heads, they have very limited binocular vision (depth perception) directly in front of them. This is why a cow might hesitate or stop at a shadow on the ground; to them, it could be a deep hole.
• Sensitivity to Motion: A cow’s eye is incredibly sensitive to sudden movements. A flapping tarp or a person waving their arms can trigger a flight response because their panoramic vision is designed to detect any movement that might indicate a predator.

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Health and Care: What to Look For

In the image, the eye appears clear and bright, which is a sign of a healthy animal. However, cattle are prone to certain eye conditions that farmers and veterinarians watch for:

1. Infectious Bovine Keratoconjunctivitis (Pinkeye): A highly contagious bacterial infection that causes redness, tearing, and cloudiness.
2. Squamous Cell Carcinoma (Cancer Eye): Often found in cattle with white faces (like Herefords) who have less pigment around their eyes to protect them from UV radiation.
3. Physical Trauma: Scratches from hay, brush, or dust can lead to ulcers if not treated.

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Summary of Bovine Eye Features

Feature	Function	Benefit
Horizontal Pupil	Wide field of view	Predator detection while grazing
Nigra Corpora	Built-in sunshading	Reduces glare in open fields
Tapetum Lucidum	Light reflection	Superior low-light/night vision
Lateral Placement	330-degree vision	Eliminates most blind spots