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Solar System Observing

Articles about how to understand, find and see solar system objects including planets, the Moon, the Sun, asteroids, meteors, and comets with binoculars, telescopes, and the naked eye.

Snapshot of a Waning Gibbous Moon

February 5, 2018 by Brian Ventrudo Filed Under: Solar System

A waning gibbous Moon, 71% illuminated, on Feb. 5, 2018. Click to open in a new window.

I looked out the window this morning and saw the Moon hanging clear and bright in a crisp and dry winter sky. So, of course, I had to take a picture!

Here you see the history of the ancient solar system etched like geological hieroglyphs into the face of our nearest celestial neighbor. The dark regions, the maria (or seas), are younger than the heavily cratered light-colored regions of the terrae (or highlands). The large dark region at the upper left is Oceanus Procellarum (the Ocean of Storms), which is capped by Mare Imbrium (Sea of Rains) to the north and Mare Nubium (Sea of Clouds) and Mare Humorum (Sea of Moisture) to the south. To the right in this image, closer to the shadow beyond the terminator, the line between night and day on the Moon, you can see the circular Mare Serenitatis (Sea of Serenity), below which is Mare Tranquillitatis (Sea of Tranquility). All these seas are lowlands flooded with lava after major meteor impacts some 3 billion years ago. The highlands are older and heavily peppered with craters from the days when the solar system was a more crowded and dangerous place.

You can see a few large craters here also. At the extreme western edge of the Moon (left in this image) you see the dark and worn crater Grimaldi. Copernicus, above and left of center, is a white bulls-eye bathed in full sunlight. Artistotle and Eudoxus are stacked on top of each other at the top, near the terminator. Theophilus is beautifully shadowed along the terminator just below center, while Maurolycus and Tycho grace the highlands to the south.

In this image, the Moon is nearly 5 days past full and 71% illuminated. The image was snapped by aiming a Nikon D750 camera out the window with a Nikon 200mm-500mm f/5.6 lens at 500mm, f/8, 1/2000s, ISO400. Cropped and lightly processed in Adobe Lightroom. Who says astrophotography has to be hard?

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Filed Under: Solar System craters, lunar seas, moon

Field Notes from a First-Time Eclipse Watcher

August 25, 2017 by Brian Ventrudo Filed Under: Solar System

An anxious astronomer awaits totality.

“Dad, you finally saw a total solar eclipse. Now you’re a real astronomer”, said my younger daughter in the minutes after the August 21 eclipse.

It was a joke, of course, but I still winced. This was a sore point with me. Forty-five years of stargazing, on and off, and I’d seen thousands of sights in the sky from earthbound satellites to the Moon, from icy flotsam from the outer solar system to the colorful cloud bands of Jupiter, and all manner of wonders of the deep sky including galaxies billions of years older than our solar system. But I’d never seen a total solar eclipse [Read more…] about Field Notes from a First-Time Eclipse Watcher

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Filed Under: Solar System essay, solar eclipse

Guide to Observing Saturn in 2017

June 22, 2017 by Brian Ventrudo Filed Under: Solar System

saturnMany casual observers get hooked on amateur astronomy after a first look at Saturn through a telescope.  More than a few have looked through my small refractor on a night of good seeing and asked of Saturn, “Is it real?”

Oh, it’s real, all right.  And incredibly beautiful… the color, the proportions, the apparent 3D perspective of this grand icy world.  It is arguably the finest sight accessible with a small telescope. The planet reached opposition on June 15, 2017 and will remain bright and large in a telescope over the next few months. Here’s how to find it and see it in a small telescope.

[Read more…] about Guide to Observing Saturn in 2017

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Filed Under: Solar System observing guide, saturn

A Guide to Observing Comet 45/P Honda–Mrkos–Pajdušáková

January 5, 2017 by Brian Ventrudo Filed Under: Solar System

Comet 45P/Honda-Mrkos-Pajdusakova imaged by amateur astronomer Tim Puckett in 2011.
Comet 45P/Honda-Mrkos-Pajdusakova imaged by amateur astronomer Tim Puckett in 2011.

A little periodic comet is visiting the inner solar system over the next few months. Comet 45/P Honda–Mrkos–Pajdušáková, a tiny piece of ice and dust left over from the earliest days of the solar system, moves periodically around the Sun every 5.25 years. It made its closest approach to the Sun on December 31, 2016 and it’s visible now. As it passes close to Earth in February, it will brighten and appear to move quickly across the sky from day to day. You’ll need binoculars to see it, but it’s worth following this little leftover hunk of the early solar system [Read more…] about A Guide to Observing Comet 45/P Honda–Mrkos–Pajdušáková

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Filed Under: Solar System comet, solar system

Venus and the “New Year” Crescent Moon

January 2, 2017 by Brian Ventrudo Filed Under: Solar System

venus-moon-new-year-2017
Venus and the crescent Moon on the evening of January 1, 2017, imaged from Bethesda, MD.

The waning of the first day of 2017 sees the slender crescent Moon, rounded out by Earthshine, and the brilliant planet Venus in the western sky after sunset. Venus puts on quite a show this month as it reaches greatest eastern elongation on January 12 and lies some 47° east of the Sun. The planet then grows in brightness to magnitude -4.7 by month’s end. That’s as bright as the planet ever gets, bright enough to cast shadows on a dark night.

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Filed Under: Solar System moon, venus

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