Astro Bob 3:54 pm, Apr. 22, 2021

Astro Bob: Celebrate Earth Day in the moonlight

The moon helps us understand how good we have it on Earth

A couple watch a bright Lyrid meteor flash overhead during the 2013 shower. The Lyrids are the longest-observed of all meteor showers, dating back to 687 B.C. or more than 2,700 years ago. (John Chumack)

Astro Bob 1:43 pm, Apr. 20, 2021

Astro Bob: April showers bring Lyrid meteor flowers

Gemini is one the 12 constellations of the zodiac and represents two inseparable brothers from ancient Greek myth. The word Gemini comes from the Latin "geminos," meaning twins. (Urania's Mirror)

Astro Bob 2:57 pm, Apr. 18, 2021

Astro Bob: Let the moon deliver you to Gemini's doorstep

New processing techniques bring out fine details in the Veil Nebula's delicate threads and filaments of ionized gas photographed with the Hubble Space Telescope. Images taken through five different filters highlight light emitted by ionized oxygen (blues) and ionized hydrogen and nitrogen (reds). (ESA / Hubble & NASA, Z. Levay)

Astro Bob 5:28 pm, Apr. 15, 2021

Astro Bob: The Veil Nebula — Beauty in destruction

A fragile-looking crescent appears low in the western sky at dusk in March 2019. (Bob King)

Astro Bob 3:18 pm, Apr. 13, 2021

Astro Bob: How to feel the rhythm of the moon

The rear hazard-avoidance camera on the Mars Perseverance rover took this picture of what looks like a rainbow on April 4, 2021. It actually turned out to be a lens flare. (NASA / JPL-Caltech)

Astro Bob 11:43 am, Apr. 11, 2021

Astro Bob: Mystery rainbow on Mars explained

Immediately after the Perseverance rover released the Ingenuity helicopter it backed off so the craft could charge its batteries using the power of sunlight. (NASA / JPL-Caltech)

Astro Bob 4:07 pm, Apr. 8, 2021

Astro Bob: NASA preps Mars chopper for historic first flight

The Spring Triangle is big and easy to find and points the way to three prominent constellations of the April sky. (Bob King)

Astro Bob 2:03 pm, Apr. 7, 2021

Astro Bob: Star-hopping with the Spring Triangle and Great Diamond

See one or see them both! The waning crescent moon passes below Saturn and then Jupiter on April 6th and 7th at dawn. This view shows the sky facing southeast about an hour before sunrise. (Stellarium)

Astro Bob 2:45 pm, Apr. 5, 2021

Astro Bob: Waning moon makes back-to-back pairings with Jupiter and Saturn at dawn

This image of the interstellar comet 2I/Borisov was taken with the European Southern Observatory’s Very Large Telescope in late 2019, when comet passed near the Sun. Since it was travelling around 108,700 miles per hour (175,000 kph) the background stars appear as streaks of light as the telescope followed the comet’s trajectory. The colors result from combining photos taken in different colors and composited into a single image. (ESO / O. Hainaut)

Astro Bob 2:51 pm, Apr. 1, 2021

Astro Bob: Comet Hale-Bopp meets its match in interstellar Comet Borisov

Starlink satellites make multiple trails over Brazil in this time exposure taken on Dec. 10, 2019. Concern is growing over how the rapid increase in the number of satellites orbiting the Earth has artificially brightened the night sky. Currently, 60 new Starlinks are launched about every two weeks. At upper right, the camera also captured a bright meteor at the same time. (Egon Filter / CC BY-SA 4.0)

Astro Bob 1:55 pm, Mar. 30, 2021

Astro Bob: New study shows satellites are making the night sky brighter

The Full Worm Moon sets in the western sky on Sunday morning, March 28. Watch it return tonight around sunset. The light of the rising sun illuminates trees and buildings in the foreground. (Bob King)

Astro Bob 12:39 pm, Mar. 28, 2021

Astro Bob: Full Worm Moon wriggles into view at sunset March 28

A small section of a rayed arc in the March 13th aurora briefly brightens into a narrow beam. (Bob King)

Astro Bob 2:46 pm, Mar. 25, 2021

Astro Bob: Full-moon aurora plus Venus returns as the 'Evening Star'

This is an artist concept of the interstellar object 'Oumuamua, which is shaped like a pancake and likely made of solid nitrogen ice. (William Hartmann)

Astro Bob 8:06 pm, Mar. 23, 2021

Astro Bob: Interstellar visitor 'Oumuamua may be a 'nitrogen pancake' from an exo-Pluto

Subtle changes in Saturn's cloud bands and brightness from 2018 to 2020 point to a transition from summer to fall. Look closely in the planet's polar region (top) and you can see how the number and thickness of the bands varies. The yellow equatorial region also brightens from left to right in these Hubble Space Telescope photos. (NASA / ESA)

Astro Bob 2:19 pm, Mar. 22, 2021

Astro Bob: Watching the seasons change at Saturn

The aurora often begins with an unassuming greenish arc just 5-10° above the northern horizon. If it fades away, the show's probably over, but if it slowly intensifies, stick around. (Bob King)

Astro Bob 8:39 pm, Mar. 18, 2021

Astro Bob: Auroras may bring in spring

NASA astronaut Don Pettit made this 72-image composite photo while onboard the ISS in April 2012. During the time exposures, cities show as yellow streaks and lightning from thunderstorms as blue flecks. The green rim is airglow, caused by oxygen and other atoms releasing light after being stimulated by solar ultraviolet (UV) light during the daytime. The station slowly rotates as it orbits the Earth, which creates the concentric star trails that mimic star trails recorded in photos taken from the ground. (NASA)

Astro Bob 1:15 pm, Mar. 17, 2021

Astro Bob: You're in luck this St. Pat's Day! The Space Station's back

Many math-minded folks celebrate the mathematical constant π (pi) on March 14 by baking a pie. The first three digits of pi are 3.14, the same as the date March 14. (Evan Shelhamer / CC BY-SA 2.0)

Astro Bob 2:28 pm, Mar. 14, 2021

Astro Bob: Enjoy a slice of crescent moon pi / More auroras predicted

Astronomers have discovered new hints of a giant, scorching-hot planet orbiting Vega, one of the brightest stars in the night sky. (Center for Astrophysics / Harvard & Smithsonian)

Astro Bob 3:59 pm, Mar. 10, 2021

Astro Bob: Massive, hot planet may orbit Vega

One of the early spring sky's largest and most delicate sights is the zodiacal light, a hazy cone-shaped glow that reaches up from the western horizon to Mars and the Pleiades star cluster. It's comprised of comet and asteroid dust backscattered by sunlight, similar to how a cloud of dust raised by a car in front of you glows against the sun. The photo was made at 7:45 p.m. March 7 facing west. (Bob King)

Astro Bob 2:31 pm, Mar. 8, 2021

Astro Bob: What's up in the sky this week, March 8-14

The green flash appears at the moment of sunrise on March 5, 2021 over the Wisconsin shoreline of Lake Superior. The brilliant burst of green light lasted about 1.5 seconds. (Bob King)

Astro Bob 1:39 pm, Mar. 7, 2021

Astro Bob: Emerald fire at dawn — how to see the elusive green flash

Jupiter and Saturn return to the morning sky in early March. Both planets are now visible very low in the southeastern sky about 45 minutes before sunrise. Friday morning, March 5, Mercury and Jupiter undergo an exceptionally close conjunction. (Stellarium)

Astro Bob 11:36 am, Mar. 4, 2021

Astro Bob: Planet kings Jupiter and Saturn return at dawn; Apophis flyby this weekend

In July 2020, Parker Solar Probe’s wide-field camera photographed a bright rim around the edge of the planet that may be nightglow — light emitted by oxygen atoms high in the atmosphere when they recombine into molecules on the nightside. The prominent dark feature in the center of the image is Aphrodite Terra, the largest highland region on Venus. Bright streaks are likely high-speed subatomic particles called cosmic rays, sunlight reflected by bits of space dust, and particles of material bouncing off the spacecraft’s structures after impact. The dark spot at lower left is an artifact from the WISPR instrument. (NASA/Johns Hopkins APL/Naval Research Laboratory/Guillermo Stenborg and Brendan Gallagher)

Astro Bob 10:49 am, Mar. 2, 2021

Astro Bob: NASA's Parker probe sees things it shouldn't on Venus

Mars sidles up to the Pleiades star cluster on Feb. 26. The two will hang close this coming week. (Bob King)

Astro Bob 1:32 pm, Feb. 28, 2021

Astro Bob: Mars pals up with the Pleiades

Another Snow Moon rises over ice shards on Lake Superior on Feb. 19, 2019. (Bob King)

Astro Bob 1:15 pm, Feb. 25, 2021

Astro Bob: Take the Full Snow Moon observing challenge

...