Table of contents for Space.com Collection in Space.com Collection

Get ready to explore the wonders of our incredible universe. The Space.com Collection is packed with amazing astronomy, incredible discoveries and the latest missions from space agencies around the world. From distant galaxies, to the planets, moons and asteroids of our own solar system – you’ll discover a wealth of facts about the cosmos, and learn about the new technologies, telescopes and rockets in development that will reveal even more of its secrets. Space.com launched 20 years ago and fast became the premier source of space exploration, innovation and astronomy news, chronicling – and celebrating – humanity’s ongoing expansion across the final frontier. For us, exploring space is as much about the journey as it is the destination.…

Nearly 14 billion years ago, there was nothing and nowhere. Then, all of a sudden, due to a random fluctuation in a completely empty void, a universe exploded into existence. Something the size of a subatomic particle inflated to an unimaginably huge size in a fraction of a second, driven apart by negative-pressure vacuum energy. Scientists call this theory for the origin of the universe the Big Bang. What we call the “observable universe” (or the “Hubble Volume”) is the spherical region, about 90 billion light-years in diameter, that is centered on any given observer. This is the only part of the universe in which light has had time to reach the observer in the 13.8 billion years since the universe began. Since the universe’s expansion is accelerating, objects are…

Is our universe unique? From science fiction to science fact, there is a concept that suggests that there could be other universes besides our own, where all the choices you made in this life played out in alternate realities. The concept is known as a “parallel universe,” and is a facet of the astronomical theory of the multiverse. The idea is pervasive in comic books, video games, television and movies. Franchises ranging from “Buffy the Vampire Slayer” to “Star Trek” and “Doctor Who” to “Digimon” use the idea to extend plotlines (see the boxout on page 33 for more pop culture examples). There actually is quite a bit of evidence out there for a multiverse. First, it is useful to understand how our universe is believed to have come to…

Ever since the discovery of Pluto in 1930, kids grew up learning about the nine planets of our solar system. That all changed starting in the late-1990s, when astronomers began to argue about whether Pluto was a planet. In a highly controversial decision, the International Astronomical Union ultimately decided in 2006 to classify Pluto as a “dwarf planet,” reducing the list of “real planets” in our solar system to eight. However, astronomers are now hunting for another planet in our solar system, a true ninth planet, after evidence of its existence was unveiled on 20 Jan 2016. The so-called “Planet Nine,” as scientists are calling it, is about ten times the mass of Earth and 5,000 times the mass of Pluto. The order of the planets, starting nearest the Sun…

Mars is the fourth planet from the sun. Befitting the Red Planet’s bloody color, the Romans named it after their god of war. In truth, the Romans copied the ancient Greeks, who also named the planet after their god of war, Ares. Other civilizations also typically gave the planet names based on its color – for example, the Egyptians named it “Her Desher,” meaning “the red one,” while ancient Chinese astronomers dubbed it “the fire star.” The bright rust color Mars is known for is due to iron-rich minerals in its regolith – the loose dust and rock covering its surface. The soil of Earth is a kind of regolith, too, albeit one loaded with organic content. According to NASA, the iron minerals oxidize, or rust, causing the soil to…

URANUS IS TILTED ON ITS SIDE Uranus appears to be a featureless blue ball upon first glance, but this gas giant of the outer solar system is pretty weird upon closer inspection. First, the planet rotates on its side for reasons scientists haven’t quite figured out. The most likely explanation is that it underwent some sort of one or more titanic collisions in the ancient past. In any case, the tilt makes Uranus unique among the solar system planets. Uranus also has tenuous rings, which were confirmed when the planet passed in front of a star (from Earth’s perspective) in 1977; as the star’s light winked on and off repeatedly, astronomers realized there was more than just a planet blocking its starlight. More recently, astronomers spotted storms in Uranus’ atmosphere…

SINGULARITY At the very centre of a black hole, matter has collapsed into a region of infinite density called a singularity. All the matter and energy that falls into the black hole ends up here. The prediction of infinite density by general relativity is thought to indicate the breakdown of the theory where quantum effects become important. EVENT HORIZON This is the radius around a singularity where matter and energy cannot escape the black hole’s gravity: the point of no return. This is the ‘black’ part of the hole. PHOTON SPHERE Although the black hole itself is dark, photons are emitted from nearby hot plasma in jets or an accretion disc (see below). In the absence of gravity, these photons would travel in straight lines, but just outside the event…

Ranging from dark energy to cosmic rays to the uniqueness of our own solar system, there is no shortage of cosmic oddities. The journal Science summarized some of the most bewildering questions being asked by leading astronomers today. In no particular order, here are eight of the most enduring mysteries in astronomy WHAT IS DARK ENERGY? Dark energy is thought to be the enigmatic force that is pulling the cosmos apart at ever-increasing speeds, and is used by astronomers to explain the universe’s accelerated expansion. This elusive force has yet to be directly detected, but dark energy is thought to make up an estimated 73 percent of the universe. WHY IS THE SOLAR SYSTEM SO BIZARRE? As alien planets around other stars are discovered, astronomers have tried to tackle and…

For two minutes, NASA astronaut Leroy Chiao could see nothing but the bluemarbled Earth swirling above his head. “Surreal” is how he described the moment. Chiao was in the middle of a lengthy spacewalk to assemble part of the International Space Station, an ambitious orbiting laboratory the likes of which had never been seen before. November 20th 2018 marked the 20th anniversary of the launch of the International Space Station’s first component, made possible by the contribution of hundreds of engineers, space shuttle astronauts like Chiao, international support and the crews who continue launching up to this day. The station itself has been continuously occupied since Nov. 2nd 2000. As we reflect on what the space station has afforded humanity – diplomacy, progress in human spaceflight and discoveries in the…

NASA’s Opportunity rover has officially concluded its 15-year mission on Mars, the agency announced in February 2019. Eight months after a raging dust storm incapacitated Opportunity’s solar panels, leaving it unable to communicate with Earth, NASA has stopped waiting for it to wake up and will no longer listen for signals from the rover. Opportunity, NASA’s longest-running Mars rover, outlived its twin rover, Spirit, which went silent in 2010 after getting stuck in a sand trap and running out of power. Both rovers launched to the Red Planet in 2003 and are collectively known as NASA’s Mars Exploration Rovers. The twin rovers made some remarkable scientific discoveries over the course of their missions on the Red Planet. Here we’ll focus on some of the stranger things Opportunity and Spirit have…

Swimming through a group of galaxies more than 200 million light-years away from Earth is the so-called “jellyfish” galaxy named ESO 137-001. This celestial jellyfish is a spiral galaxy much like the Milky Way, but it has long “tentacles” of hot gas streaming away from the galactic disk. Scientists aren’t sure how the gas is being stripped away, but NASA’s James Webb Space Telescope may be able to shed some light on the origin of those tentacles by studying them in unprecedented detail after its planned launch in 2021. This view combines visible-light imagery from the Hubble Space Telescope and X-ray data from the Chandra X-ray Observatory. Colorful cosmic “fireworks” decorate the night sky over the La Silla observatory in Chile in this gorgeous image by the European Southern Observatory’s…

The cosmic microwave background (CMB) is thought to be leftover radiation from the Big Bang, or the time when the universe began. As the theory goes, when the universe was born it underwent a rapid inflation and expansion. The universe is still expanding today, and the expansion rate appears different depending on where you look. The CMB represents the heat left over from the Big Bang. You can’t see the CMB with your naked eye, but it is everywhere in the universe. It is invisible to humans because it is so cold, just 2.725 degrees above absolute zero (minus 459.67 degrees Fahrenheit, or minus 273.15 degrees Celsius.) This means its radiation is most visible in the microwave part of the electromagnetic spectrum. ORIGINS AND DISCOVERY The universe began 13.8 billion…

MERCURY The closest planet to the Sun, Mercury is only a bit larger than Earth’s Moon. Its day side is scorched by the Sun and can reach 840 degrees Fahrenheit (450 Celsius), but on the night side, temperatures drop to hundreds of degrees below freezing. Mercury has virtually no atmosphere to absorb meteor impacts, so its surface is pockmarked with craters, just like the Moon. Over its four-year mission, NASA’s MESSENGER spacecraft has revealed views of the planet that have challenged astronomers’ expectations. STATS DISCOVERY: KNOWN TO THE ANCIENTS AND VISIBLE TO THE NAKED EYE NAMED FOR: MESSENGER OF THE ROMAN GODS DIAMETER: 3,031 MILES (4,878 KM) ORBIT: 88 EARTH DAYS LENGTH OF DAY: 58.6 EARTH DAYS VENUS The second planet from the Sun, Venus is terribly hot, even hotter…

Earth, our home, is the third planet from the sun. It’s the only planet known to have an atmosphere containing free oxygen, oceans of water on its surface and, of course, life. Earth is the fifth largest of the planets in the solar system. It’s smaller than the four gas giants – Jupiter, Saturn, Uranus and Neptune – but larger than the three other rocky planets, Mercury, Mars and Venus. Earth has a diameter of roughly 8,000 miles (13,000 kilometers) and is round because gravity pulls matter into a ball. But, it’s not perfectly round. Earth is really an “oblate spheroid,” because its spin causes it to be squashed at its poles and swollen at the equator. Water covers roughly 71 percent of Earth’s surface, and most of that is…

We may finally know how much the Milky Way weighs. Estimates of our home galaxy’s heft vary widely, from about 500 billion times the mass of our sun to 3 trillion solar masses. The number is so tough to pin down because about 85 percent of the Milky Way’s mass is made up of dark matter – mysterious stuff that neither absorbs nor emits light (hence the name). ”We just can’t detect dark matter directly,” Laura Watkins, of the European Southern Observatory in Garching, Germany, explained in a statement. “That’s what leads to the present uncertainty in the Milky Way’s mass – you can’t measure accurately what you can’t see!” “85 PERCENT OF THE MILKY WAY’S MASS IS MADE UP OF MYSTERIOUS DARK MATTER” So, Watkins and her colleagues came…

In January 2019, scientists announced the discovery of the energetic core of a distant galaxy that shatters the record for the brightest object in the early universe, blazing with the light equivalent to 600 trillion suns. Researchers identified the object – a black-hole-powered object called a quasar, among the universe’s brightest inhabitants – because of a chance alignment with a dim galaxy closer to Earth that magnified its light. The quasar is 12.8 billion light-years away, and it shines at the heart of a forming galaxy during an early part of the universe’s history called the epoch of reionization, when the first stars and galaxies began to burn away a haze of neutral hydrogen across the cosmos. Researchers announced its discovery at the January 2019 American Astronomical Society’s winter meeting…

At the center of our solar system lies the sun, the yellow star that sustains life on our planet. The sun’s many magnetic fields distort and twist as our parent star rotates on its axis. When these fields become knotted together, they burst and create so-called sunspots. Usually, these sunspots occur in pairs; the largest can be several times the size of Earth’s diameter. As the temperature on the sun’s surface rises and falls, the plasma of our star boils and bubbles. Particles escape from the star from the sunspot regions on the surface, hurtling particles of plasma, known as solar wind, out into space. It takes these winds around 40 hours to reach Earth. When they do, they can cause the dramatic displays known as the aurora borealis. SUNSPOTS…

On April 12, 1961, humanity became a spacefaring species when cosmonaut Yuri Gagarin blasted into orbit on a 108-minute flight high above Earth. So Gagarin set the original record – first person in space. But over the years, people have notched many other records as our species has extended its toehold in the cold depths of space. Here’s a look at some of these marks, from the oldest person in space to the most consecutive days spent away from terra firma. FIRST SPACEWALKS The first-ever spacewalk was performed by Alexei Leonov, who performed a 12-minute spacewalk during Voshkod 2 on March 18, 1965. The astronaut later said that he had trouble getting back inside the spacecraft (his spacesuit ballooned) and that he also was close to getting heatstroke, but he…

NASA’s James Webb Space Telescope, scheduled for launch in 2021, will probe the cosmos to uncover the history of the universe from the Big Bang to alien planet formation and beyond. It will focus on four main areas: first light in the universe, assembly of galaxies in the early universe, birth of stars and protoplanetary systems, and planets (including the origins of life.) The James Webb Space Telescope (JWST) will launch on an Ariane 5 rocket from French Guiana, then take 30 days to fly a million miles to its permanent home: a Lagrange point, or a gravitationally stable location in space. It will orbit around L2, a spot in space near Earth that lies opposite from the sun. This has been a popular spot for several other space telescopes,…

NASA’s next 60 years will probably be very different than its first six decades. When the agency opened for business in 1958, private spaceflight was just a sci-fi dream. But companies such as Elon Musk’s SpaceX and Jeff Bezos’ Blue Origin are working to make that dream a reality and open the space frontier to huge numbers of people for the first time. What role will NASA play in the private sector’s liftoff? Space.com recently talked to three commercial-spaceflight experts to get some ideas. First, people should understand that about 75 percent of the worldwide space enterprise is already commercial, said Scott Hubbard, an adjunct professor in the Department of Aeronautics and Astronautics at Stanford University. This includes the satellites belonging to DirecTV and Sirius XM radio. What’s new s”is…

The Big Bang theory is the leading explanation about how the universe began. At its simplest, it says the universe as we know it started with a small singularity, then inflated over the next 13.8 billion years to the cosmos that we know today. Because current instruments don’t allow astronomers to peer back at the universe’s birth, much of what we understand about the Big Bang theory comes from mathematical formulas and models. Astronomers can, however, see the “echo” of the expansion through a phenomenon known as the cosmic microwave background. While the majority of the astronomical community accepts the theory, there are some theorists who have alternative explanations besides the Big Bang – such as eternal inflation or an oscillating universe. The phrase “Big Bang theory” has been popular…

Perhaps the greatest revelation in the past hundred years of studying the universe is that our home changes and evolves with time. And not just in minor, insignificant ways like stars moving about, gas clouds compressing and massive stars dying in cataclysmic explosions. No, our entire cosmos has changed its fundamental character more than once in the distant past, completely altering its internal state at a global – that is, universal – scale. Take, for instance, the fact that at one time in the foggy, ill-remembered past, there were no stars. BEFORE THE FIRST LIGHT We know this simple fact because of the existence of the cosmic microwave background (CMB), a bath of weak but persistent radiation that soaks the entire universe. If you encounter a random photon (a bit…

From all the grains of sand on Earth to the number of stars in the sky, With the addition of only a few zeros, big numbers transform from “countable” to the subject of guesswork. Eventually, their existence pulls at our imagination and requires the crafting of intricate scenarios. They may or may not have a presence in the universe. From the tiniest specks in the universe to the biggest numbers humanity has ever conceived, here are some of the numbers that make up our universe. 1 ZERO The total energy that makes up the microbes, plants, oceans, planets, stars and galaxies (in other words, our entire universe) is probably… zero. That’s because the negative energy in the universe most likely cancels out the positive energy. Physicists consider light, matter and…

“LEARN ENOUGH ABOUT IMPACTS, AND WE MAY BE ABLE TO SAVE OUR OWN SKINS THE NEXT TIME AROUND” Asteroid impacts have a bad reputation here on Earth – it’s the dinosaurs’ signature public relations victory – but it’s the moon that really bears the scars of living in our messy neighborhood. That’s because Earth has an arsenal of forces that slowly wear away the craters left behind by impacts. And that’s frustrating for scientists who want to better understand the debris hurtling around our solar system. So a 2019 study uses the pockmarked lunar surface to trace the history of things smashing into both our Moon and Earth, finding signs that our neighborhood got a lot messier about 290 million years ago. “It’s a cool study that talks about our…

Robots aren’t the only ones getting a ticket to Mars. A workshop group of scientists from government agencies, academia and industry have determined that a NASA-led manned mission to Mars should be possible by the 2030s. However, in late 2017, the Trump administration directed NASA to send people back to the moon before going to Mars. NASA is now more focused on a concept called the Lunar Orbital Platform-Gateway that would be a moon-based space station and headquarters for further space exploration. Robotic missions to the Red Planet have seen much success in the past few decades, but it remains a considerable challenge to get people to Mars. With current rocket technology, it would take several months for people to travel to Mars, and that means they would live for…

The sun lies at the heart of the solar system, where it is by far the largest object. It holds 99.8 percent of the solar system’s mass and is roughly 109 times the diameter of the Earth – about one million Earths could fit inside the sun. BThe visible part of the sun is about 10,000 degrees Fahrenheit (5,500 degrees Celsius), while temperatures in the core reach more than 27 million F (15 million C), driven by nuclear reactions. One would need to explode 100 billion tons of dynamite every second to match the energy produced by the sun, according to NASA. The sun is one of more than 100 billion stars in the Milky Way. It orbits some 25,000 light-years from the galactic core, completing a revolution once every…

For the first time ever, humanity has photographed one of these elusive cosmic beasts, shining light on an exotic space-time realm that had long been beyond our ken. “We have seen what we thought was unseeable,” Sheperd Doeleman, of Harvard University and the Harvard-Smithsonian Center for Astrophysics, said during a press conference at the National Press Club in Washington, DC on 10 April 2019. Doeleman directs the Event Horizon Telescope (EHT) project, which captured the epic imagery. These four photos, which were unveiled at press events around the world and in a series of published papers, outline the contours of the monster black hole lurking at the heart of the elliptical galaxy M87. The imagery is mind-blowing enough in its own right. But even more significant is the trail the…

There’s a weird mix of order and chaos in the light blasted out by gamma-ray bursts (GRBs), brief but intense outbursts are associated with black hole formation. Research published in January 2019 shows that GRB photons tend to be polarized – that is, most of them oscillate in the same direction. But, surprisingly, this direction changes over time. “The results show that, as the explosion takes place, something happens which causes the photons to be emitted with a different polarization direction,” Merlin Kole, one of the new study’s lead authors, said in a statement. “What this could be, we really don’t know,” he added. The most powerful GRBs are unleashed when massive stars go hypernova – an especially intense type of supernova – and then collapse to form black holes.…

The World Magnetic Model (WMM) is the name of the updated representation of the magnetic field of Earth. The magnetic pole is moving erratically out of the Canadian Arctic and toward Siberia so unpredictably that it has taken scientists by surprise. That 2015 update was supposed to remain valid until 2020, Arnaud Chulliat, a geomagnetist at the University of Colorado Boulder and the National Oceanic and Atmospheric Administration’s (NOAA) National Centers for Environmental Information, told Nature. It’s no news that the pole is moving; long-term records from London and Paris (kept since 1580) show that the north magnetic pole moves erratically around the rotational north pole over periods of a few hundred years or longer, Ciaran Beggan, a geophysicist with the British Geological Survey who is involved in WMM updates,…

Throughout its time in space, the iconic Hubble Space Telescope – which launched on April 24, 1990 – has provided spectacular views of the cosmos and revealed exceptional insights about the universe. But there were also moments when it looked as though decades of work, plus billions of taxpayer dollars, might suddenly slip down the drain, and there were worries that the project might fail completely. But Hubble overcame those obstacles to become one of the most successful telescopes ever built, both in terms of its scientific return and its impact on the public. And after more than 25 years of operation, Hubble’s best days may still be ahead of it, astronomers say. “Even the most optimistic person to whom you could have spoken back in 1990 couldn’t have predicted…

Between March 2015 and March 2016, a man spent a total of 357 hours being poked and prodded: sacrificing blood and urine, sweating through sprints and letting others read his journals – oh, and living on the International Space Station. The man was Scott Kelly, and with his Russian counterpart, Mikhail Kornienko, he spent a total of 340 days living in space as part of NASA’s first attempt to understand how such long stints without gravity affect the human body. But while the men returned to Earth nearly three years ago, scientists are still trying to figure out what they’ve learned. A new paper lays out the tests built into the “One-Year Mission” of Kelly and Kornienko and contextualizes it in the context of longer spaceflight – like that which…

JUNE JUNE 3 NEW MOON JUNE 17 Full Moon. The “Strawberry Moon” will reach full phase at 4:31 a.m. EDT (0831 GMT). JUNE 5 An Ariane 5 rocket provided by Arianespace will launch the DirecTV 16 and Eutelsat 7C communications satellites from Europe’s spaceport in Kourou, French Guiana. JUNE 21 JUNE 27 JUNE 12 NASA will conduct a test of the Orion spacecraft’s Launch Abort System at Cape Canaveral Air Force Station in Florida. JUNE 19 Moon occults Saturn. The moon will pass in front of the ringed planet for skywatchers in parts of South America and southern Africa. Meanwhile, skywatchers in other parts of the world will see the two bodies make a close approach, or a conjunction. JUNE 24 Three Expedition 59 crewmembers will…