Astro Bob

Venus, the lunar crescent and Regulus join forces at dawn tomorrow morning (Oct. 13) in the eastern sky. Stellarium I love October. The sun rises late which means you can get up early. For many of us sunup occurs between 7 and 7:30, making it easier to see pretty happenings in the dawn sky. For instance, tomorrow morning (Oct. 13) the waning crescent moon will join 1st magnitude Regulus, Leo's brightest star, and brilliant Venus in the east to make an attractive sight.   If you're up around 6 a.m. you'll see the trio in the growing light and may find it's just what you need to start the day. The moon is three days from new and will look like a bright rind edging the bottom of the darker, earth-lit disk. Direct sunlight illuminates the crescent; light reflected from the Earth dimly brightens the remainder.    Venus is a tiny gibbous "moon" in a telescope this month. Stellarium     As ever, Venus has a magnetic draw on the eyes, while dimmer Regulus completes...

  Mars can help us find the variable star Mira in the constellation Cetus the sea monster. The two are currently just a fist and a half apart. Mira is a pulsating variable star that physically expands and contracts, brightening and fading over a period of 332 days. Bob King The Red Planet squares off with a red giant this month. Mars is currently just 15° (a fist and a half) above and to the left of the one of the best-known variable stars, Mira the Wonderful. Mira gives cause for wonder because it occasionally glows as bright as the North Star and but then disappears from naked-eye view a few months later.  Mira animation. Merikanto / Wikimedia Commons. CC BY-SA 4.0 Mira's light varies because it pulsates. and changes in size which affects its temperature and brightness. Picture blowing up a balloon, letting out some of the air and then blowing it back up again. When Mira contracts it heats up and brightens, and when it expands it cools and fades.  You need a small tel...

Astro Bob entries on the Duluth News Tribune website today (Oct. 9). Before I share sky events I wanted to update you about the Astro Bob blog. I started writing it Feb. 2008 when I was a photographer and photo editor at the Duluth News Tribune. It became part of my daily work and contribution to the website. When I retired in 2018 I continued writing the blog as a freelancer for the newspaper, for which I'm grateful. Recently, the blog was transferred to a new weblink  where you can read the current entry and the full archive back to 2008. But there's a caveat. Not long ago, the newspaper website changed from free access to a paid subscription. Those of you who've tried to read the blog recently may have run into the "paywall."  With a digital subscription you can read Astro Bob anytime you want. Without one, access is limited to three visits a month. For the time being you'll still be able to read the blog on Blogger, Facebook and Twitter for free, but that...

A poplar tree in full fall regalia frames the waning gibbous moon this morning. Bob King I've written about seeing the moon in the daytime sky before. I hope you don't mind if I take another swing at the topic. Did you see the moon this morning? Just amazing. It caught my eye around 8 a.m. high in the southwestern sky couched in deep blue and framed by autumnal colors. Portrait of the full moon if the sun's light were suddenly extinguished. Can you find it? Stellarium with additions by the author For the next two hours as I went about errands it hung in clear view opposite the sun, illuminated by the light kindled by fusing atoms in its core. At a glance you could see one of the most important differences between a planet (or moon) and a star. A star makes its own energy and beams it across space in all directions. Moons and planets reflect a small portion of that light back, which renders them visible. Otherwise they'd appear as black silhouettes against the stars.  Th...

Mars leaves a bright glitter path on Lake Superior near Duluth, Minn. on a recent night. Bob King All eyes are on Mars this week. On Oct. 6 it will reach it's minimum distance from Earth of 38.6 million miles (62.1 million km) and shine incredibly bright, besting even mighty Jupiter. The two planets won't be this close again nor will Mars be as brilliant until September 2035. A week later on Oct. 13 Earth and Mars will be at opposition, precisely lined up together on the same side of the sun and only slightly less close. When the faster Earth laps Mars every couple years, the two planets come closest and Mars is said to be  at opposition . It lies directly opposite the sun in the sky — rising at sunset and setting at sunrise — and remains visible all night. Due to Mars's more strongly elliptical orbit (see below) some oppositions, like the current one, are closer than others. The closest are called perihelic while distant ones are aphelic. NASA Earth is the faster orbiting ...

You can't miss the twinkly, red-orange gleam of Arcturus at dusk in the western sky. Physically and culturally it's one of the most interesting stars in the sky. DSS2 / Aladin Sky Atlas Look in the western sky as soon as it gets dark, and you'll see a single bright orange star. That's Arcturus , fourth brightest in the night sky. It shines at magnitude 0 and lies 36.7 light years from Earth. Twinkles of its light that enervate your retinas tonight began their journey in 1983 when the world's population was 4.7 billion (it's now 7.8 billion) and before there was an internet.  Arcturus is the brightest star in Boötes the Herdsman. If you have any trouble finding it just follow the arc of the Dipper's handle.  Stellarium Arcturus is a red giant star about 25 times the size of the sun. If Arcturus took over our star's job at the center of our solar system it would span more than a dozen degrees, larger than the bowl of the Big Dipper. Although its surface te...

Bennu is a small, diamond-shaped asteroid with carbon and water-rich rocks related to carbonaceous meteorites that have landed on the Earth. NASA will gather the first Bennu sample this month and return the material to Earth for analysis in 2023. NASA/Goddard/Univ. of Arizona A new month brings fresh excitement. On Oct. 20, NASA's OSIRIS-REx spacecraft will attempt to grab its first sample of dust and rock from the asteroid Bennu in a daring touch-and-go maneuver. If you're not familiar with Bennu it's a tiny, carbon-rich asteroid just 1,610 feet across (490 meters) currently located 201 million miles from Earth.  Its orbit passes close enough to our planet astronomers classify it as potentially hazardous  object with a  cumulative 1-in-2,700 chance of impacting Earth between 2175 and 2199.  These are two examples of CM2 carbonaceous (carbon-rich) meteorites found on Earth: Jbilet Winselwanfrom Western Sahara, and Aguas Zarcas, which fell in Costa Rica on April 23, ...