尤里之夜的凸月 A gibbous moon on Yuri's Night
International Day of Human Space Flight
Sixty-one years ago today Yuri Gagarin became the first human to see Earth from space, with a view likely similar to this image of the waning gibbous moon from the International Space Station. With a call of 'Poyekhali!' ('Off we go!'), Gagarin launched into low Earth orbit in his Vostok 3KA spacecraft, making history in less than two hours with a complete trip around the planet.
'International Day of Human Space Flight' is observed today by astronomy lovers of all nationalities, it becomes an international celebration held every April 12 to commemorate milestones in space exploration.
Hey neighbor, it's World Space Week!
Space is a big, lonely place, so it's nice to know we have neighbors. The pictured Andromeda Galaxy is our Milky Way's closest—right next door at 2.5 million light years away. Our cordial relationship with Andromeda goes back about 10 billion years to when both galaxies were still forming. But trouble is brewing: Andromeda is on a collision course with the Milky Way, due for impact in 4 billion years. This neighborhood's about to get rough…
Sometime in the 4 billion years we have left (preferably this World Space Week, October 4-10), we encourage you to turn your attention to the stars, whether on a trip to the countryside, the planetarium, or your backyard. World Space Week's 2021 theme is 'Women in Space'—and it's also the theme of today's quiz. How much do you know about the final frontier's famous females?
Last stop before leaving the solar system
Official confirmation of Neptune's presence in our solar system came on September 23, 1846. Credit for this discovery inspired a dust-up in the international astronomy community, as scientists from both Britain and France claimed they had been the first to see the 8th and most-distant planet in our solar system. Eventually peace was brokered, and credit is now shared between the two factions. But those 19th-century astronomers were using solar system coordinates first recorded by Galileo in 1612. The Italian polymath correctly mapped Neptune's position more than 200 years earlier using a less powerful telescope. Galileo mistook Neptune for a star—but his coordinates prompted many stargazers who came along after him to look in the correct direction and identify Neptune.
Gazing down on planet Earth
It's Earth Day today and we are high above the blue marble looking down on the border between Arkansas and Mississippi. Those small, blocky shapes are towns, fields, and pastures–the teal green is the mighty Mississippi River. Anyone who has flown in the window seat of an airplane and has gazed down at Earth below might wonder why the colors in this image are so unreal. That's because they are. These images were taken in 2013 by Landsat 7, a NASA satellite that uses thermal infrared sensors to help scientists better distinguish flora, fauna, water, and manmade objects. For almost 50 years, NASA has been using satellite imagery to understand how climate change and population growth are affecting our fragile planet. These satellites help NASA see where deforestation and wildfires are happening, where glaciers are melting, and how rising waters are encroaching on cities.
The biggest cause of these changes? According to NASA, it's us. Since the first Landsat launched in 1972, the Earth's population has almost doubled, from 4 billion people then to 7.8 billion today. But there is some good news to mark this Earth Day: The Mississippi River we see here is much less toxic now than it was back in 1972, thanks to environmental laws and regulations.
Infrared Jupiter, erupting Io
To celebrate World Space Week, we're featuring this montage of images of Jupiter courtesy of the New Horizons probe's flyby of the planet in 2007. If Jupiter looks a little different than you're used to seeing, it's because it was imaged using the space probe's near-infrared imaging spectrometer. In this false-color image, Jupiter's high-altitude clouds, like its stormy Great Red Spot, are rendered white, while deeper cloud formations take on reddish hues. The planet's innermost moon, Io, is captured in a true-color composite image during one of its frequent volcanic eruptions. A close look will show lava is glowing red beneath the blue and white plume of particles being ejected into the moon's thin atmosphere.
Space Week is a UN-recognized event that runs each year from October 4, which is the anniversary of the launch of Sputnik in 1957, to October 10, the anniversary of the signing of the Outer Space Treaty in 1967. This year's theme is 'Satellites Improve Life.'
Celebrating 30 years of eye-opening images
On this day in 1990, the Hubble Space Telescope entered orbit in the cargo bay of the space shuttle Discovery. Shortly thereafter, it began its continuing mission to capture images of our universe from low Earth orbit, free of the obstructions of clouds and the distortions of the atmosphere. Like its namesake, the great astronomer Edwin Hubble, the Hubble Space Telescope has transformed our understanding of the cosmos. Some of the telescope's greatest contributions include its Deep Field Images—which peer back billions of lightyears—or its with jaw-dropping images of objects closer to home, like the one on today's homepage, which shows a maelstrom of glowing gas and dark dust within one of the Milky Way's satellite galaxies, the Large Magellanic Cloud.
NASA estimates that Hubble's mission will continue for another 10-20 more years. Next year, it will be joined in orbit by the James Webb Space Telescope, which will be able to peer even farther into space and with greater sensitivity across more wavelengths.
NASA astronaut works on International Space Station during a spacewalk in 2006 (© NASA)
A stroll above the stratosphere
If this photo from 200-plus miles above Earth dizzies you, imagine how it felt to be Alexei Leonov on March 18, 1965. The Soviet cosmonaut achieved the first-ever extravehicular activity (EVA—but you and I just call it a spacewalk). He spent about 20 minutes outside the orbiting Voskhod 2 capsule. It was the ultimate risk: no one knew just what could happen to a human body in the vacuum of space. Near heatstroke, drenched with sweat, and with his suit dangerously inflating, Leonov barely made it back inside the airlock.
Of course, the art of EVA has been perfected since, and that vertigo-inducing panorama is now the view from the office for those aboard the International Space Station. The spacewalker you see here isn't Leonov but NASA's Robert Curbeam busily replacing a faulty component. On this mission in 2006, Curbeam set a record with four EVAs in one spaceflight, spending over 24 hours outside the vehicle. Since the ISS's first spacewalk in 1998, over 227 EVAs have been performed by a large cast of astronauts—including a milestone excursion in 2019 that employed the first all-female crew.
Too awesome to be a planet
Pluto was first spotted on this day in 1930 by Clyde Tombaugh, a 23-year-old astronomer at Lowell Observatory in Flagstaff, Arizona. Because it’s so far away—about 40 times as far from the sun as Earth is—scientists knew relatively little about Pluto until the New Horizons spacecraft reached it in 2015. In a flyby study, the craft spent more than five months gathering detailed information about Pluto and its moons. What did they find out? There’s a heart-shaped glacier, blue skies, spinning moons, mountains as high as the Rockies, and it snows—but the snow is red.
Once thought to be one of nine full-fledged planets orbiting our sun, in 2006, Pluto was stripped of its planetary status and reclassified as merely a 'dwarf planet.' (Sorry, Pluto.) Though it may no longer be considered a true planet, it’s still the largest dwarf planet of our solar system and holds plenty of mysteries waiting to be discovered.
A star blows a bubble
This giant space bubble is being blown by a massive star visible at the 10 o'clock position inside it. Already over 7 light-years across and expanding at a rate of over 4 million mph, the 'bubble' is actually the shock wave created when expanding hot gas (or stellar wind) hits the cold, interstellar gas that surrounds it. The Bubble nebula was discovered in 1787 by William Herschel. The star inside is living fast and will die young (for a star)—it will likely detonate as a supernova in only 10 to 20 million years. This image was taken in 2016 by the Hubble Space Telescope to mark the 26th anniversary of Hubble's launch into Earth orbit by the STS-31 space shuttle crew. We're showing it to mark the last day of World Space Week, an annual 'international celebration of science and technology, and their contribution to the betterment of the human condition.
Images from NASA's Juno spacecraft as it swoops by Jupiter
For the start of World Space Week, today's homepage features a composite of images taken by NASA's Juno probe as it swooped past Jupiter. Jupiter, the largest planet in our solar system, also has the largest number of moons: 79. Jupiter is the Roman counterpart to Zeus, and so the planet's major moons are named after Zeus's, shall we say, extra-marital partners. So, when it came time to name NASA's most ambitious Jupiter probe, they decided to name it after his wife, Juno, so that she could keep an eye on him. Every 53 days in the course of its wide and complex orbit, the Juno probe makes its closest approach, snapping shots like these as it speeds past the gas giant in just two hours. World Space Week starts on the anniversary of the launch of the very first space probe, Sputnik, which entered orbit around the Earth on October 4, 1957.