On Oct. 4th, 1957, at 10:29 PM Moscow time, the Soviet Union successfully launched Sputnik 1 into space on a repurposed R-7 rocket. The world’s first artificial satellite, Sputnik was about 22 inches (58 centimeters) in diameter and weighed 184 pounds (84 kilograms). Although there were no scientific instruments aboard, the transmitter it carried sentContinue reading "Oct. 4th, 1957: Sputnik launches"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 3: Dione transits Saturn We’re back at Saturn this evening with the planet as the main attraction as the ringed world reaches opposition today at 8 A.M. EDT. Rising around sunset and setting around sunrise, it is visible all night inContinue reading "The Sky Today on Sunday, October 4: Saturn reaches opposition"

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A 12-ton rocket loaded with a 1-ton warhead, the V-2’s successful launch would prove to be exceptionally significant to both the military and to space exploration. On Oct. 3, 1942, the V-2 was fired from Peenemunde, Germany – its fourth test, and the first to succeed. The rocket rose to an altitude of 60 milesContinue reading "Oct. 3, 1942: The V-2 successfully launches"

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Huang Dandan, taken from Shennongjia, Hubei, China The gegenschein, a faint glow of sunlight scattered back toward Earth by dust grains in the inner solar system, sits in Aquarius at the point directly opposite the Sun in this all-sky view. The Milky Way arcs across the center, and the red light at bottom is aContinue reading "Gegenschein over Shennongjia"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 2: Venus stands still The small moon Dione transits Saturn starting just before midnight EDT. Tenth-magnitude Dione crosses the far northern region of the planet, beginning its journey just minutes after 11:40 P.M. EDT and taking about an hour and aContinue reading "The Sky Today on Saturday, October 3: Dione transits Saturn"

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If a train leaves the station in Exeter, England, headed south toward Newton Abbot five years before the railway line opens, how long until anyone figures out that it didn’t happen? Well, evidently about 155 years. A report on magnetic storms, published in Nature in 1871, described an incident thought to be the earliest recordedContinue reading "Case closed on long-standing space weather mystery"

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What type of lighting emits the least amount of light pollution? Peter BladoTacoma, Washington First, use a good lighting fixture, one that is a “full cutoff.” That means there is no direct upgoing light at all. It generally also means there is very little light just below the horizontal, which is the kind of lightContinue reading "How can I reduce my personal contribution to light pollution?"

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An ancient solar eclipse changed the course of a military conflict when it cast a shadow on a battle over Corinth between the Spartans, commanded by Cleombrotus, and the invading Persians, led by Xerxes I. Herodotus wrote that, “while [Cleombrotus] was offering sacrifice to know if he should march out against the Persians, the SunContinue reading "Oct. 2, 480 B.C.E.: A eclipse causes a retreat"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 1: Perseus’ Double Cluster The brilliant planet Venus stands stationary against the background stars of Virgo at 10 A.M. EDT.  Together with Mercury, Venus is visible for a short time in the western sky after sunset, but you’ll want a clearContinue reading "The Sky Today on Friday, October 2: Venus stands still"

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Looking for a sky event this week? Check out our full Sky This Week column.  September 16: Triangle in the sky The Moon passes 0.6° south of the bright star Antares at 9 A.M. EDT. By evening, our satellite sits near the border of Scorpius and Ophiuchus, some 6° east (to the upper left) of Antares. TheyContinue reading "The Sky Today on Thursday, September 17: The Moon and the Scorpion"

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Today I’ll be telling you about 10 of my favorite autumn deep-sky objects, with suggestions for viewing them. I hope you’ll enjoy this list, and I’ll share some other deep-sky favorites of mine from time to time in the future. What’s a large telescope? The notion of what’s big changes from observer to observer, butContinue reading "Autumn observing targets for large telescopes"

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When the Artemis 2 crew splashed down in the Pacific Ocean on April 10, the excitement was palpable — Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen had swung around the Moon, broken a human spaceflight distance record, and come home safely. But for the Artemis program, it was just the beginning. Between April’sContinue reading "Why we need in-orbit refueling to return to the Moon"

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On June 16, 1888, Alexander Friedmann was born in St. Petersburg, Russia. An keen student from a young age, Friedmann studied mathematics and meteorology at St. Petersburg State University and the Aerological Observatory in Pavlovsk. After air force service in World War I, Friedmann taught at several institutions and traveled to discuss his research. InContinue reading "Sept. 16, 1925: Death of Alexander Friedmann"

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Looking for a sky event this week? Check out our full Sky This Week column.  September 15: View the false dawn Rising around sunset and highest in the early-morning hours before sunrise is the constellation Triangulum. This tiny triangular star pattern is perfect for evening or morning observers: Around 10 P.M. local daylight time, it’s high enoughContinue reading "The Sky Today on Wednesday, September 16: Triangle in the sky"

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In a groundbreaking announcement, the U.S. Space Force stated publicly on Monday, Sept. 14, that it currently has on-orbit weapons in space. Department of the Air Force Secretary Troy Meink’s keynote address at the 2026 Air and Space Cyber Conference focused on plans to modernize the Air Force against AI-powered weapons and capabilities wielded byContinue reading "U.S. confirms it has weapons in orbit"

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Telescope Live gives astrophotographers access to world-class imaging data.

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Mike Selby/Warren Keller, taken from El Sauce Observatory, Chile NGC 6902 is a rarely-imaged face-on spiral galaxy about 130 million light-years away in the southern constellation of Sagittarius. Its outer blue arms are filamentary, winding around a bright, yellow core of older stars. The image was taken with a 17-inch PlaneWave CDK astrograph and LRGBContinue reading "A feathery spiral in Sagittarius"

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After over 7,000 days in space, the Cassini mission ended on Sept. 15, 2017. Since its Oct. 15, 1997 launch, the spacecraft had returned a wealth of new knowledge and images of Saturn and its moons. Thanks to Cassini’s observations, researchers discovered liquid methane lakes on Titan, the potential habitability of Enceladus and the geysersContinue reading "Sept. 15, 2017, Cassini’s Grand Finale"

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Looking for a sky event this week? Check out our full Sky This Week column.  September 14: Connect four The time around the equinox is one of the best opportunities to catch sight of the ethereal zodiacal light, the soft glow generated by dust that orbits the Sun along the plane of the solar system, the ecliptic.Continue reading "The Sky Today on Tuesday, September 15: View the false dawn"

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Rocket launches this week On Monday, Sept. 14 at 9:21 p.m. EST, Avio — a publicly traded Italian aerospace company headquartered near Rome — is set to launch a Vega C rocket from the Guiana Space Centre in French Guiana, carrying two Earth-observation satellites for the European Space Agency (ESA). The first, Sentinel-3C, is theContinue reading "Europe launches two Earth-observation satellites amidst a busy week for China"

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