Astro Bob's Astronomy for Everyone

Astro Bob's Astronomy for Everyone For the latest on "what's up in the night sky" please go to duluthnewstribune.com/lifestyle/astro-bob

Tight squeeze for the moon and Pleiades The most famous star cluster in the sky pals it up with the waning moon Wednesda...
09/02/2026

Tight squeeze for the moon and Pleiades

The most famous star cluster in the sky pals it up with the waning moon Wednesday night. If you're up late, you'll see them together in the northeastern sky. Moonlight will dim the cluster, but if use binoculars, you'll fit them both in the same field of view. They'll be just 4° apart.

If you wait till Thursday at the start of dawn, cluster and rocky orb will be much closer together — just one moon-diameter apart. Why? During the night the moon has traveled along its orbit east in the direction of the Pleiades., shrinking the distance between them. Nothing stands still up there.

Fear not Phobos. Marvel instead.Mars has two tiny moons, Phobos and Deimos, named for the gods of fear and panic. Both n...
09/02/2026

Fear not Phobos. Marvel instead.

Mars has two tiny moons, Phobos and Deimos, named for the gods of fear and panic. Both names fit right in with the Martian war-theme. Phobos is the larger of the two but still tiny at just 17 miles across. On Aug. 12, the Perseverance Rover captured this amazing photo of Phobos transiting the sun. A transit is a little bit like an eclipse, except that the blocking object is much smaller than the background object.

The video shows another Phobos transit, also recorded by Perseverance, made on April 2, 2022. Because Phobos orbits Mars in just 7 hours and 39 minutes, transits are brief, lasting only 30 seconds or less.

Saturn and the moon level with each otherMonday night, Aug. 31 look low in the east after the moon rises. You'll see Sat...
08/31/2026

Saturn and the moon level with each other

Monday night, Aug. 31 look low in the east after the moon rises. You'll see Saturn, which looks like a bright star, a little more than a fist to its right. They rise together in Pisces. Above the pair is one of the fall season's most recognizable star patterns called the Great Square. It's part of Pegasus the Flying Horse and shaped like a baseball diamond. Get to know that diamond and you can use it as steppingstone to a slew of new constellations rising in the east. We'll explore them by and by as temperatures drop and leaves begin to fall.

Roman space candle on a missionIt felt reassuring to see that the Nancy Grace Roman Space Telescope's successful liftoff...
08/30/2026

Roman space candle on a mission

It felt reassuring to see that the Nancy Grace Roman Space Telescope's successful liftoff this Sunday morning. I worry about our country sometimes, so it helped to see an important science mission like this one off to a good start.

Named for Dr. Nancy Roman, NASA's first female executive and chief of astronomy, the observatory will perform tests and calibrations over the next 90 days. We should see the first images in January 2027. Roman was best known as the "mother of Hubble" because of her fierce advocacy for space-based astronomy.

Her namesake telescope's mirror is identical in size to the Hubble (94-inches) but has a field of view 100 times as large. This lets it survey the universe 1,000 times faster in both visible AND infrared light.

During its 5-year mission it will probe the mysteries of dark matter and dark energy and uncover heaps of new planets. To date astronomers have discovered more than 6,300 exoplanets. The Roman Telescope is expected to add 100,000 more!

The orbiting observatory will use a high-end coronagraph, an instrument that masks a star's light so astronomers can search for and photograph Saturn-and-Jupiter-sized planets orbiting nearby. For an unobstructed view of the cosmos the Roman telescope will "park" in the same region of space as the Webb Space Telescope at what's called the L2 Lagrange point. Here it will have an unimpeded view of the universe.

(Photos: 1. Takeoff on Sunday, Aug. 30 - NASA/John Kraus. 2. Dr. Roman at Goddard Space Flight Center back in the day. 3. Comparison of the Hubble field of view and Roman Telescope. 4. The L2 Lagrange point, current location of the Webb Space Telescope and future home for the Roman Telescope.

Aurora alert — G2 storm possible Friday night, Aug. 28 The hoped-for aurora never showed during last night's lunar eclip...
08/29/2026

Aurora alert — G2 storm possible Friday night, Aug. 28

The hoped-for aurora never showed during last night's lunar eclipse. But after we all went to bed, the shockwave arrived,and Earth's magnetic envelope, the magnetosphere, has been tensing and flexing ever since.

The chances for aurora look excellent this Friday evening, so if you have clear skies and live in the northern third of the U.S. or in Canada, you'll likely see some green or even a few rays in the northern sky.

And if you don't see it, your phone will capture it. Phone cameras see better than our eyes because they're taking time-exposure pictures several seconds long that allow faint light to accumulate. Our eyes "expose" the sky for only about a tenth of a second. Unfortunately, moonlight will temper the view. The moon is just a day past full and rises at dusk.

We have clouds in Duluth, but if you see the aurora please send us a note. Thanks! The photo is from earlier this month.

What a difference a shadow makes I hope you were able to see at least some of last night's lunar eclipse. We won't have ...
08/28/2026

What a difference a shadow makes

I hope you were able to see at least some of last night's lunar eclipse. We won't have another one as deep for the Americas until June 26, 2029. The moon looked smoky orange to my eye. What colors did you see? I put the eclipsed and uneclipsed moons side by side so you can see how dramatically Earth's shadow changes the moon's appearance.

I enjoyed how the sky and the forest around me grew darker and darker by the minute until my own shadow was so faint it was difficult to see. The diminishing light deepened the night's mystery. Then the moon slowly regained its strength until it flooded the landscape and dashed the stars — a symphony of light and dark in multiple movements.

At maximum eclipse, the Milky Way and stars were SO bright. I took the fisheye photo during this time. Before it all began, the Full Sturgeon Moon quietly rose above a placid Lake Superior in Duluth.

Very nice, colorful lunar eclipse from Duluth. The sky really got dark! No aurora however. More photos later.
08/28/2026

Very nice, colorful lunar eclipse from Duluth. The sky really got dark! No aurora however. More photos later.

Tonight's Trifecta — Full Moon, deep eclipse, and a side of northern lightsBesides the deep partial eclipse Thursday nig...
08/27/2026

Tonight's Trifecta — Full Moon, deep eclipse, and a side of northern lights

Besides the deep partial eclipse Thursday night (Aug. 27) there's a distinct possibility for a G2 (moderate) auroral storm. Normally, it would be watered down by the light of the full moon. But during the eclipse, the sky will darken and the Milky Way return to view from about 10:30-11:30 p.m. Central Time centered on maximum eclipse.

Any aurora at that time should be easily visible in the lower half of the northern sky for observers in the northern third of the U.S. I'll post a live photo here if the lights show up. Hope so!
The moon pic was my attempt to capture a colorful lunar corona two nights ago with a cell phone. Not always the best instrument but it's sure handy.

Don't miss Thursday night's colorful, near-total lunar eclipse You don't need anything but your eyes and a comfortable c...
08/26/2026

Don't miss Thursday night's colorful, near-total lunar eclipse

You don't need anything but your eyes and a comfortable chair to watch the eclipse tomorrow night. This eclipse occurs about 2 weeks after the Aug. 12 new moon and total solar eclipse. The interval between new moon and full moon, when lunar eclipses occur, is about 2 weeks. That's close enough in time for the moon to align again with the Earth and sun to produce a second eclipse. Eclipses nearly always come in pairs.

On Thursday night, the moon passes behind Earth into its shadow, which has two parts — the outer penumbra and inner umbra. You'll see the first penumbral shading around 9 p.m. Central Time as a soot-like smudge along the moon's left (east) side. The umbra or core shadow is much darker and looks like a nibble that gradually becomes a big bite.

At greatest eclipse the umbra will darken 96% of the moon, leaving only a bright upper edge like you see in the photo. As the moon slips deeper in the umbra it will turn a beautiful smoky red or red-orange. This is caused by sunlight refracted (bent) by the atmosphere into the umbra from every single sunrise and sunset around the perimeter of our planet. It's an amazing sight. Wishing you clear skies!

Redheads shine together — Mars and Betelgeuse at dawnBefore Jupiter rose the other morning (Aug. 24), Mars and Betelgeus...
08/25/2026

Redheads shine together — Mars and Betelgeuse at dawn

Before Jupiter rose the other morning (Aug. 24), Mars and Betelgeuse made a lovely pair of red "stars" in the eastern sky. Mars is currently in Gemini the Twins. Betelgeuse is the bright star in Orion's shoulder. We've know for some time that Mars gets its hue from iron oxide (rust) in dust blown hither and yon around the planet by Martian winds.

Several billion years ago, when Mars began to dry up, ultraviolet light from the sun broke apart water molecules (H2O) in the atmosphere. The hydrogen escaped into space, while the heavier oxygen combined with iron in rocks to create rust.

However, recent research indicates that the iron oxide may have instead formed directly when water reacted with iron in ancient Martian lakes and rivers, so it may be even older.

Betelgeuse is red because its surface is much cooler than the sun's. It gives off more red light the same way an electric stove coil glows deep red at the low setting and bright orange when turned up to high. Also, titanium oxide in the star's atmosphere absorbs blue and green light and allows only the orange and red colors to pass. These add to Betelgeuse's ginger light.

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