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Science & Space

Planets, missions, and the physics of the universe — from the inner solar system to deep space.

The Periodic Table

The periodic table is the organized array of the chemical elements in order of increasing atomic number — the number of protons in the nucleus — from hydrogen (1) to oganesson (118), with a recurring pattern of properties called the periodic law. Dmitri Mendeleev's table of 1869 arranged the 70 elements then known by atomic weight, left gaps for missing ones and famously foretold gallium, scandium and germanium. Henry Moseley's X-ray work of 1913 showed the true ordering principle was atomic number. IUPAC now maintains the table, its 18 groups and the standard atomic weights (latest revision 2024), and approves new names — nihonium, moscovium, tennessine and oganesson joined in 2016 to complete the seventh row. Today 118 elements are known, and researchers hunt for elements 119 and 120 and the long-predicted island of stability.

25/25 claims verified 14 min read·

The Sun

The Sun is the G2 V yellow-dwarf star that holds the solar system together, containing more than 99 percent of its mass. In its core, hydrogen fuses into helium at about 15 million °C; energy takes some 170,000 years to work its way out, and the visible photosphere glows at about 5,500 °C. Around it, an 11-year cycle of magnetic activity rhythmically builds and clears the sunspots, tracked as a numbered series since Solar Cycle 1 in 1755 and now observed by NOAA's Space Weather Prediction Center. Cycle 25 began in December 2019; the 2019 prediction panel expected a peak of 115 sunspots in July 2025, while the smoothed sunspot number has already peaked so far at 160.9 in October 2024. The record of human observation stretches back to the first telescope drawings of 1610, through Schwabe's patient 43-year register and Carrington's 1859 flare, to a fleet of spacecraft — SDO, SOHO, STEREO, Hinode and Wind — joined by Parker Solar Probe, which touched the corona in 2021 and flew within 6.1 million kilometres of the surface on 24 December 2024, and ESA's Solar Orbiter, which returned the first close-up images of the Sun's poles in June 2025. This fact base collects the numbers, dates and quoted evidence behind that story.

25/25 claims verified 15 min read·

The Solar System

The solar system is the Sun and everything held by its gravity: eight planets, five officially named dwarf planets, hundreds of moons, and millions of asteroids and comets. It formed about 4.6 billion years ago when a cloud of interstellar gas and dust collapsed into a spinning disk, and the Sun gathered more than 99% of the matter. Nearest the Sun are the rocky terrestrial planets — Mercury, Venus, Earth and Mars — followed by the giants Jupiter, Saturn, Uranus and Neptune. Beyond Neptune lie the Kuiper Belt and the vast Oort Cloud. In 2006 the International Astronomical Union defined what a planet is, reducing the census from nine to eight and reclassifying Pluto as a dwarf planet; NASA's New Horizons has since shown Pluto as a complex world.

25/25 claims verified 12 min read·

Jupiter

Jupiter is the fifth planet from the Sun, the largest and oldest planet in the solar system, and more than twice as massive as all the other planets combined. Its hydrogen-helium atmosphere is banded by jet streams thousands of kilometres deep, its Great Red Spot has been observed for centuries, and its magnetosphere is the largest structure in the solar system. Juno has been orbiting Jupiter since 2016, ESA's Juice is on its way for a 2031 arrival, and NASA's Europa Clipper will reach the Jovian system in 2030 to study the icy moon Europa.

25/25 claims verified 15 min read·

Apollo 11

Apollo 11 was NASA's first crewed Moon landing, flown 16–24 July 1969. Neil Armstrong, Michael Collins and Edwin “Buzz” Aldrin launched atop a Saturn V, and on 20 July 1969 the lunar module Eagle landed in the Sea of Tranquility while Collins orbited overhead in the command module Columbia. Armstrong and Aldrin spent 21 hours 36 minutes on the surface, collected 48 pounds of lunar material, deployed science experiments and left a flag and plaque behind. An estimated 650 million people watched the first steps on television. The crew returned on 24 July and spent 21 days in quarantine as a planetary-protection precaution.

24/24 claims verified 13 min read·

International Space Station

The International Space Station (ISS) is a modular space station assembled in low Earth orbit beginning in 1998 by the United States, Russia, Europe, Japan and Canada. It orbits at roughly 400 km altitude and 28,000 km/h, circling Earth about every 90 minutes — 16 sunrises and sunsets a day. Continuous occupation began on 2 November 2000; more than 280 people from 26 countries have visited since. The station supports research in biology, physics, materials science and human health, and serves as a testbed for technologies needed for deep-space exploration.

25/25 claims verified 18 min read·

Saturn

Saturn is the sixth planet from the Sun and the second largest in the solar system, a gas giant made mostly of hydrogen and helium with the lowest mean density of any planet — 0.69 grams per cubic centimetre, less than that of water. Its rings, almost entirely water ice, extend up to 282,000 kilometres from the planet yet stand only about 10 metres thick in the main rings, and its family of 293 confirmed moons as of August 2026 ranges from planet-sized Titan, with its thick nitrogen atmosphere and methane lakes, to Enceladus, whose geysers spray a subsurface ocean into space and supply the E ring. NASA's Cassini spacecraft orbited Saturn from 2004 to 2017 — the first spacecraft ever to do so — and its ESA-built Huygens probe made the first landing in the outer solar system, on Titan, in January 2005.

25/25 claims verified 15 min read·

The Milky Way

The Milky Way is the galaxy that contains the Solar System: a large barred spiral whose disk spans about 100,000 light-years, with roughly 100–400 billion stars and a total mass of about 1.5 trillion solar masses — most of it dark matter. Astronomers map it from the inside with ESA's Gaia mission, and test the laws of gravity on stars whipping around Sagittarius A*, the four-million-solar-mass black hole at the centre.

25/25 claims verified 12 min read·

The Big Bang

The Big Bang is the prevailing model of how the universe began: about 13.8 billion years ago the cosmos expanded from an extremely hot and dense state and has been cooling and expanding ever since. Three independent lines of evidence converge on it — the expansion of the universe described by Hubble's law, the cosmic microwave background at 2.725 K released about 380,000 years after the beginning, and the predicted abundances of hydrogen, helium and lithium forged in the first minutes. This article follows that evidence chain from Hubble's 1929 observations to the Planck and DESI results, and explains what the theory does — and does not — claim.

25/25 claims verified 14 min read·

Mars

Mars is the fourth planet from the Sun and the most explored planet beyond Earth — the only world on which robotic rovers have driven across the surface. Its landscape is defined by rust-colored dust, extinct volcanoes, vast canyons, polar ice, and evidence that rivers and lakes once flowed there. Two small moons, Phobos and Deimos, orbit close to the planet, and an armada of spacecraft has studied Mars since the first flyby in 1965.

25/25 claims verified 10 min read·

The Moon

The Moon is Earth's only natural satellite, orbiting at an average distance of 384,400 kilometers. It is tidally locked to Earth, so the same hemisphere always faces us. Its surface records billions of years of impacts and ancient volcanic plains, and its polar craters harbor water ice. On July 20, 1969, Apollo 11's astronauts became the first humans to walk on its surface.

25/25 claims verified 13 min read·

James Webb Space Telescope

The James Webb Space Telescope (JWST) is a space-based infrared observatory launched on 25 December 2021 by NASA, ESA, and CSA. From its orbit around the second Sun-Earth Lagrange point, 1.5 million kilometers from Earth, its 6.5-meter segmented gold-coated mirror and five-layer sunshield let it peer back more than 13.5 billion years to the first galaxies, probe the atmospheres of distant exoplanets, and watch stars and planets being born inside dusty clouds. Webb released its first full-color images on 12 July 2022 and has since set records that include the most distant known galaxy, JADES-GS-z14-0.

25/25 claims verified 13 min read·

Black Holes

A black hole is a region of spacetime whose gravity is so strong that nothing, not even light, can escape past its boundary, the event horizon. First imagined as 'dark stars' in the 18th century and predicted by Einstein's general relativity in 1915, black holes were long considered unobservable. Today they are studied through gravitational waves, X-ray binaries, and the orbits of stars — and were photographed directly for the first time by the Event Horizon Telescope in 2019 (M87*) and 2022 (Sagittarius A*).

25/25 claims verified 14 min read·

DNA

DNA (deoxyribonucleic acid) is the hereditary material of humans and almost all other organisms — a long molecule of two interwound strands whose four chemical bases, adenine, guanine, cytosine and thymine, encode the instructions for building and maintaining life. Its structure was not the work of one team: Friedrich Miescher isolated "nuclein" in 1869, Phoebus Levene mapped the nucleotide building blocks, Erwin Chargaff found the pairing regularities, Rosalind Franklin and Maurice Wilkins captured the crucial X-ray images, and James Watson and Francis Crick assembled the double-helix model published in Nature on 25 April 1953. Meselson and Stahl later proved replication semiconservative, Nirenberg cracked the genetic code, and the Human Genome Project (1990–2003) read the roughly 3 billion bases of the human genome, completed without gaps by the T2T consortium in 2022.

25/25 claims verified 14 min read·

Hubble Space Telescope

The Hubble Space Telescope is a NASA/ESA observatory launched on 24 April 1990 aboard the space shuttle Discovery. Orbiting about 483 km above Earth, its 2.4-meter mirror has made more than 1.7 million observations, from the deep fields that revealed thousands of galaxies to measurements that fixed the universe's expansion rate at near one percent precision. Astronauts serviced the telescope five times between 1993 and 2009 — the first mission correcting the spherical aberration that blurred its early images — and since June 2024 Hubble has operated in one-gyro mode, continuing its work alongside the James Webb Space Telescope.

25/25 claims verified 15 min read·

Photosynthesis

Photosynthesis is the process by which green plants, algae and cyanobacteria transform light energy into chemical energy, converting carbon dioxide and water into sugars and releasing oxygen. It runs in two linked stages: the light-dependent reactions in the thylakoid membrane, where water is split and sunlight drives electron transport that makes ATP and NADPH, and the Calvin–Benson cycle in the stroma, where the enzyme Rubisco fixes CO2 into sugars. The oxygen released comes from water, not carbon dioxide — a point settled with 18O-labelled water in 1941. Photosynthesizers split into oxygenic forms (plants, algae, cyanobacteria) and anoxygenic bacteria such as green and purple sulfur bacteria, which use hydrogen sulfide instead of water. Land plants add further strategies — C3, C4 (Hatch–Slack) and CAM — that differ in how they supply CO2 to Rubisco. Photosynthesis sets the scale of the biosphere: global net primary production is estimated at about 104.9 petagrams of carbon per year, and roughly half of Earth's oxygen production comes from the ocean. Efficiency figures vary with definition: the theoretical maximum conversion of solar energy to biomass is put at 4.6% for C3 and 6% for C4 photosynthesis, while realized field efficiencies are far lower.

25/25 claims verified 15 min read·