September is a month of changing seasons and outward journeys. The equinox reminds us that Earth is moving through its orbit, carrying us around the Sun on a world whose tilted axis gives us the changing seasons. The Harvest Moon lights the early autumn sky. Neptune reaches opposition, giving observers the best opportunity of the year to find that distant blue world. Woven through the month are anniversaries that changed the human story: Luna 2 reaching the Moon, Kennedy giving public voice to the lunar challenge, Viking 2 exploring Mars, Voyager 1 beginning its long journey toward interstellar space, and Galileo completing its mission at Jupiter.
The story of September is simple: human beings look into the unknown, wonder what is there, and then find a way to explore it.
September 1 — The Carrington Event — 1859
Often, when I am participating in a solar viewing outreach event—and solar observing is something that must always be carefully monitored to keep everyone safe—someone will bring up the Carrington Event as an example of just how powerful, and potentially dangerous, our Sun can be. On September 1, 1859, English astronomer Richard Carrington observed an extraordinarily brilliant white-light flare erupting on the Sun, while Richard Hodgson independently witnessed the same event. The enormous geomagnetic storm that followed on September 1 and 2 produced spectacular auroras across unusually large parts of the world and disrupted telegraph systems, in some cases causing sparks and allowing operators to continue sending messages even after disconnecting their batteries. The Carrington Event remains one of the great reminders that the Sun is not the quiet, unchanging star it may appear to be through a properly filtered telescope. It is an incredibly powerful and dynamic star, and sometimes what happens 93 million miles away can reach across space and touch our lives here on Earth.
September 3 — Viking 2 Lands on Mars — 1976
Viking 2 landed at Utopia Planitia on September 3, 1976, following Viking 1’s historic landing earlier that summer. Images from the surface were transmitted across millions of miles of space and soon appeared on television screens and in newspapers around the world, giving people on Earth another extraordinary opportunity to see the surface of Mars. Together, the Viking landers carried out the first successful long-term scientific investigations from the Martian surface, studying the landscape, weather, soil, and atmosphere while confronting a question that still calls to us today: Is there, or has there ever been, life on Mars?
September 5 — Voyager 1 Launches — 1977
Voyager 1 launched on September 5, 1977, beginning a journey that would carry it past Jupiter and Saturn and eventually into interstellar space, becoming the most distant human-made object in history. There is also a wonderful human story woven into Voyager’s nearly fifty-year journey. Dr. Linda Spilker came to JPL straight out of college in 1977 and began her career working on the Voyager mission. She would go on to work on other great missions of exploration, most notably Cassini at Saturn, but today she has come full circle as Voyager Project Scientist, once again working with the spacecraft that helped begin her career. Nearly half a century later, the Voyagers are still exploring, still carrying their Golden Records into the unknown, and one of the young scientists who was there near the beginning is helping guide them through the final chapter of one of humanity’s greatest journeys of exploration.
September 8 — Moon Near the Beehive Cluster
If you can get up early with your astrophotography rig, you may be treated to a beautiful meeting in the morning sky. Before sunrise, the waning crescent Moon appears near the Beehive Cluster, M44, in the constellation Cancer, and from some locations the Moon may pass in front of stars in the cluster. This could make a wonderful target for astrophotographers, while binocular observers can simply enjoy the delicate stars of the Beehive sharing the sky with the slender crescent Moon.
Sometimes getting out of bed before sunrise is not easy, but the universe has a way of rewarding those who make the effort to be there, just ask my daughters when I woke them up in the middle of the night to drive to the nearest dark sky from our condo in Orange County to see the huge tail of comet C/1996 B2 (Hyakutake). They still remember it to this very day.
September 10–11 — New Moon
The New Moon occurs late on September 10 in U.S. time zones and on September 11 UTC, giving observers some of the darkest skies of the month. This is the time to explore faint galaxies, nebulae, and star clusters from a dark-sky location. In the Northern Hemisphere, the Andromeda Galaxy rises into prominence, while the Ring Nebula, Dumbbell Nebula, and the magnificent Double Cluster offer rewarding views through binoculars and telescopes. Farther south, observers can explore the Small Magellanic Cloud, the great globular cluster 47 Tucanae, the Sculptor Galaxy, and the Tarantula Nebula. Wherever we live on Earth, a dark night away from city lights reminds us that the seemingly empty spaces between the stars are filled with galaxies, nebulae, and star clusters waiting to be explored.
September 11 — Surveyor 5 Lands on the Moon — 1967
Surveyor 5 landed on the Moon on September 11, 1967, and became the first spacecraft to perform an in-situ chemical analysis of material on another world. Its instruments found a composition broadly similar to terrestrial basalt, providing scientists with important new information about the nature of the lunar maria before Apollo astronauts arrived. Less than two years later, Apollo 11 astronauts would land in the same general region and bring actual lunar rocks home for scientists to study.
September 12 — Luna 2 Launches Toward the Moon — 1959
The Soviet Union launched Luna 2 on September 12, 1959. Less than 39 hours later, it reached the Moon, becoming the first human-made object to reach the surface of another world. It was a simple and incredibly bold mission: cross the space between Earth and the Moon and, for the first time in human history, touch another world. Luna 2 did not enter lunar orbit or slow down to land. It was placed on a direct trajectory toward the Moon and crossed the hundreds of thousands of kilometers separating Earth and the Moon.
September 12 — Kennedy’s Moon Speech — 1962
On September 12, 1962, President John F. Kennedy stood at Rice University and gave one of the defining speeches of the Space Age, explaining why America should accept the enormous challenge of reaching the Moon. But Kennedy’s thinking continued to evolve. A year later, concerned about the cost and questioning whether exploration had to remain a competition between nations, he proposed that the United States and Soviet Union consider going to the Moon together. Kennedy would not live to see how the story ended, leaving us with one of the great unanswered questions of the Space Age: had he lived, would the first journey to the Moon have remained an American race—or become a human mission shared between former rivals?
September 13 — Luna 2 Reaches the Moon — 1959
On September 13, 1959 UTC—September 14 in Moscow—Luna 2 wasted no time when it reached the Moon, striking the surface at about 3.3 kilometers per second, or roughly 7,400 miles per hour. Much of the spacecraft would have shattered, melted, or vaporized upon impact. But Luna 2 was never intended to survive, and it was never coming home. Its destruction was the final act of an incredibly bold mission. For the first time in human history, something conceived, designed, and built by human hands had crossed the space between worlds and physically reached another celestial body. Somewhere within that small impact site, mixed with the ancient dust and rock of the Moon, may still remain fragments of Luna 2, a reminder of the moment when humanity first reached out across the universe and touched another world.
Luna 2 did more than reach the Moon. Along the way, its instruments studied radiation and charged particles in space, while measurements near the Moon found no significant lunar magnetic field or radiation belts like those surrounding Earth. But perhaps its greatest discovery was something no instrument needed to measure: humanity had learned how to cross the space between worlds and reach another celestial body.
September 17 — Space Shuttle Enterprise Unveiled — 1976
NASA rolled out Space Shuttle Enterprise on September 17, 1976. Originally planned as Constitution, the orbiter was renamed Enterprise after a public campaign by Star Trek fans. Enterprise never flew in space, but it played a vital role in approach and landing tests that helped prepare the shuttle program.
September 18 — Voyager 1’s Earth-Moon Portrait — 1977
It is hard to believe that a spacecraft launched nearly fifty years ago is still communicating with Earth. On September 18, 1977, just thirteen days after its launch, Voyager 1 looked back and photographed Earth and the Moon together from about 7.25 million miles away. It was the first spacecraft image to capture both Earth and the entire Moon in a single frame, showing us early in Voyager’s journey that our world and its companion could be seen together as a system in space.
September 21 — Galileo Ends Its Mission at Jupiter — 2003
NASA ended Galileo’s mission on September 21, 2003, by sending the spacecraft into Jupiter’s atmosphere. Galileo had spent years exploring Jupiter and its moons, including observations that strengthened the case for a subsurface ocean beneath Europa’s ice. The spacecraft was deliberately destroyed to avoid any future possibility of contaminating Europa, one of the most intriguing worlds in the search for life beyond Earth.
September 22–23 — September Equinox
The September equinox occurs at about 00:06 UTC on September 23, which is the evening of September 22 in U.S. Central time. The Sun crosses the celestial equator heading south, beginning astronomical autumn in the Northern Hemisphere and spring in the Southern Hemisphere. Around the time of the equinox, one of the most remarkable celebrations of the Sun takes place at Chichén Itzá in Mexico, where sunlight and shadow create the appearance of a serpent descending the steps of the great pyramid of El Castillo. People have watched the changing position of the Sun for thousands of years, using its movement to understand the seasons and the passage of time. Today, the equinox remains a wonderful reminder that no matter where we live on Earth, we are all traveling together on a planet moving through space.
September 23 — Neptune Discovered — 1846
After Uranus was discovered in 1781, astronomers noticed something strange: Uranus was not moving exactly where Newton’s laws said it should. Its orbit seemed to be tugged by something unseen. Some wondered if Newton’s gravity was wrong at such great distances, but two mathematicians—Urbain Le Verrier in France and John Couch Adams in England—independently worked out a more exciting possibility: there must be another planet beyond Uranus.
Le Verrier sent his prediction to Johann Gottfried Galle at the Berlin Observatory. Galle and his assistant Heinrich Louis d’Arrest looked at the predicted position on September 23, 1846, and compared the star field with a chart. D’Arrest noticed a “star” that was not on the map. That object was Neptune.
That is what makes the discovery so powerful. Neptune was first found in the mind, through mathematics, and then found in the sky, through a telescope. It was one of the great confirmations that the universe is not chaos. It follows rules we can discover, and sometimes those rules can lead us to worlds no human eye has ever seen before.
September 25–26 — Neptune at Opposition
Neptune reaches opposition around September 26 UTC, which places the event on the evening of September 25 in U.S. Central time. This is the best time of the year to observe Neptune, although it will still require optical aid. Under steady skies, a telescope can show it as a tiny blue disk rather than just a faint point of light.
September 26 — Full Harvest Moon
The September full Moon falls on September 26 and is the Harvest Moon, the full Moon closest to the September equinox. Historically, its evening light was associated with giving farmers additional time to complete the harvest. Even today, the Harvest Moon remains one of the great seasonal markers of the year, a reminder that astronomy is not only something we do with telescopes. It is also something woven into the rhythms of human life on Earth.
September 26–27 — Moon Near Saturn
Around September 26–27, the Moon appears near Saturn in the sky, making a beautiful pairing for observers and photographers. Saturn is always one of the great treasures of the telescope, but when the Moon passes nearby, even casual skywatchers have an easy landmark to help them find the ringed planet.
September 27 — SMART-1 Launches — 2003
ESA launched SMART-1 on September 27, 2003. Unlike Luna 2, which flew a direct trajectory to the Moon in less than 39 hours, SMART-1 took the slow road, using solar-electric ion propulsion to gradually spiral away from Earth and toward the Moon. An ion engine produces only a tiny amount of thrust, but it can continue pushing a spacecraft for months or even years while using remarkably little propellant. SMART-1 took more than a year to reach lunar orbit, but along the way it helped demonstrate technologies that could make ambitious journeys through deep space more efficient. Sometimes exploring the universe is not about getting there faster. It is about discovering a better way to travel farther.
September 28 — AstroSat Launches — 2015
India launched AstroSat on September 28, 2015. It was India’s first dedicated astronomy mission, designed to observe the universe primarily in ultraviolet and X-ray wavelengths, with supporting optical observations. Its launch marked an important step in India’s growing contribution to space science and the study of the high-energy universe.
September 29 — SpaceShipOne’s First Ansari X Prize Flight — 2004
On September 29, 2004, SpaceShipOne made the first of two flights required to win the $10 million Ansari X Prize. The prize, substantially funded by entrepreneur and future space traveler Anousheh Ansari and her family, challenged privately financed teams to build a reusable spacecraft capable of carrying people into space. Just days later, SpaceShipOne completed its second successful flight and won the prize, helping open a new chapter in commercial human spaceflight. Less than two years later, Ansari would make her own journey into space, becoming the first Iranian-born person to reach space and the first female private space explorer to visit the International Space Station.
Most Significant Day: September 13
If I had to choose one day that carries the heart of the month, I would choose September 13.
On that day in 1959, Luna 2 reached the Moon. It did not land softly. It did not send back panoramic views. It did not carry people. But it crossed a boundary that had existed for all of human history. The Moon had been a light in the sky, a calendar, a symbol, a mystery, and a world seen only from a distance. Then, for the first time, something made on Earth touched it.
That is why September’s theme is Reaching Other Worlds. We imagine. We calculate. We build. We launch. And one day, what seemed impossible becomes a place we have reached.
