Brian Ventrudo

The Five Numbers That Explain a Telescope

April 4, 2020 by Brian Ventrudo Filed Under: Astronomy Equipment

A 14" Schmidt-Cassegrain telescope (credit: Celestron). — A 14″ Schmidt-Cassegrain telescope (credit: Celestron).

Before we launch into the pros and cons of the types of telescopes available to stargazers today, let’s have a quick look at 5 key numbers that describe the operation and performance of every telescope, from the junk scopes in a department store to the venerable Hubble Space Telescope. Once you understand these 5 numbers, you will understand the similarities and differences between telescopes, and you will know how to choose the best scope for your own interests and budget [Read more…] about The Five Numbers That Explain a Telescope

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The Purpose of a Telescope

April 2, 2020 by Brian Ventrudo Filed Under: Astronomy Equipment

The 8.2-m primary mirror of Yepun, Unit Telescope 4 of ESO's Very Large Telescope, after its recoating in early March — The 8.2-m primary mirror of Yepun, Unit Telescope 4 of ESO’s Very Large Telescope, after its recoating in early March

Here we cover an essential but often overlooked point about telescopes. It may seem strange to cover this, but once you understand this point, you’ll understand the trade-offs involved in choosing a good telescope for stargazing. The fact is, most beginners believe the purpose of a telescope is to magnify objects, to make them appear bigger. This is not true. What, then, is the purpose of a telescope? [Read more…] about The Purpose of a Telescope

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A Look Back at Comet Hale-Bopp

March 27, 2020 by Brian Ventrudo Filed Under: Solar System

Comet C/1995 O1 (Hale-Bopp) after sunset near the constellation Cassiopeia on March 27, 1997, three days after its closest approach to Earth (Credit: Brian Ventrudo)

At any particular time, a half-dozen or more comets are visible with a good-sized amateur telescope. But a bright comet is a once-in-a-decade event at best, and a Great Comet, one that grows bright enough to capture wide attention, is rarer still. Recently there have been two Great Comets visible to observers in the southern hemisphere, Comet McNaught in 2007 and Comet Lovejoy in 2011. But it’s been a long drought for stargazers in the northern hemisphere, where no spectacular comet has been seen since 1997 when the mighty Comet C/1995 O1, better known as Comet Hale-Bopp, barreled in from the outer solar system and put on one of the most watched celestial shows in modern history [Read more…] about A Look Back at Comet Hale-Bopp

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Hopping Double Stars in Cassiopeia

February 26, 2020 by Brian Ventrudo Filed Under: Deep Sky

White arrows point to the objects in this brief tour of the constellation Cassiopeia. Created with SkyX by Software Bisque.

When time is tight and the weather turns cold, I turn to a class of celestial objects that are very forgiving of observing conditions, light pollution, and telescope aperture: double and multiple stars. There are thousands of these objects visible during the year. Many are run-of-the-mill sights. But many more present a lovely appearance in a small telescope, revealing color, brightness contrast, and a jewel-like appearance that appeal to the artistically inclined while also packing plenty of physics and sheer challenge to the observer.

In this instalment of Cosmic Pursuits, I share with you three double and multiple stars in and around the throne of the legendary Ethiopian queen (along with a couple of extraordinary ‘bonus objects’). So grab a small telescope and head out to see them for yourself. The map above shows you where to find these relatively bright star systems and ‘bonus objects’… [Read more…] about Hopping Double Stars in Cassiopeia

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The Rosette Nebula

January 28, 2020 by Brian Ventrudo Filed Under: Deep Sky

Look to the east of mighty Orion and you’ll see the constellation Monoceros, the Unicorn. While its stars are faint, Monoceros holds a small treasure chest of superb deep-sky sights for backyard stargazers. Perhaps the most striking is the Rosette Nebula, an achingly beautiful blossom of glowing gas and dust where new stars are forming. The Rosette is an immense nebula, some three times larger than the Orion Nebula and three times farther away. As you see in the image above by Terry Hancock, the nebula overlaps the star cluster NGC 2244 which has formed within the nebula and blown a bubble to give us a look inside. While hard to see the Rosette visually, even in large telescopes, the nebula is an excellent photographic target and the cluster is a superb sight [Read more…] about The Rosette Nebula

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