Basic astronomy and night sky information
Small Maksutov-Cassegrain telescopes are a godsend for urban observers who need a compact scope with good optics. And “Maks” are back in style, so there’s a good selection on the market. But Maks aren’t for everyone. Here’s how to tell if a Mak is right for you [Read more…] about Maksutov-Cassegrain Telescopes
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When the members of the great unwashed masses think of an astronomical telescope, they usually think of a refractor. With a large glass objective lens at the top of the tube and an eyepiece down at the bottom, refractors are the most robust and conceptually simplest type of telescope. They offer amazingly crisp views of the Moon and planets and double stars. But they are not for everyone. This short article goes through the pros and cons of refractors for astronomy and helps you decide if such a telescope is right for you [Read more…] about Refracting Telescopes for Astronomy
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While a couple of promising comets have fizzled out this spring, the slow and steady Comet C/2017 T2 (PanSTARRS) is keeping astrophotographers happy as it moves through the northern constellation Ursa Major. On May 24, the comet passed the lovely pair spiral galaxies M81 and M82 near the bowl of the Big Dipper. The event was framed spectacularly in the above image by Terry Hancock and Tom Masterson using the Takahashi E-180 Astrograph at Grand Mesa Observatory in Colorado. This image is a testament to a high level of expertise and it shows how astrophotography at the hands of skilled and talented practitioners can approach high art [Read more…] about Galaxies and Comet C/2017 T2 (PanSTARRS)
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Reflecting telescopes (or reflectors) collect light using a curved mirror at the rear of the main tube rather than a lens at the front end. Isaac Newton gets credit for inventing the first reflecting telescope in the late 17th century. He used a second small diagonal mirror to direct light out the side of the telescope to an eyepiece. His immensely practical design, now called the Newtonian reflector, is the main type of purely reflecting telescope in use today by amateur astronomers [Read more…] about Newtonian Reflectors and Dobsonian Telescopes
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The galaxy M61 has done it again: it’s produced another supernova, the eighth such event since 1926. That makes this lovely face-on spiral galaxy in the Virgo cluster one of the most prolific supernova producers of the past century.
The supernova, cataloged as SN2020jfo, was discovered on May 6, 2020 at the Zwicky Transient Facility at Palomar Observatory near San Diego. Upon discovery, the exploding star was magnitude 14.7. It’s since brightened to about 14.3. To see it visually requires at least a 10″ telescope, but it is relatively easy to take a snapshot with an astronomy camera and a much smaller scope. I took the 20x10s stack of images at the top with an 85mm Tele Vue refractor, an 0.8x focal reducer, and an inexpensive ZWO ASI290MM camera.
One of the more prominent members of the Virgo cluster, Messier 61 is a lovely barred spiral with winding arms knotted with star-forming nebula and clouds of blue-white stars. It’s a starburst galaxy, one wracked with prodigious star formation which explains why so many supernovae have been seen here. With lots of massive, fast-burning young stars forming, it’s inevitable that they reach their spectacular end as a Type II supernova during which the star, as it runs out of fuel, collapses and snaps back in a spectacular explosion. It releases as much energy in a few weeks as our Sun releases in its entire 10 billion year life span.
M61 is about the same size as our Milky Way and lies about 52 million light years away, so the progenitor star detonated when Earth was in the Eocene period back when Australia and Antarctica were still connected and most of the planet was covered in lush forest.
And since astronomy is not just a matter of contemplating space but also time, keep in mind that the light from thousands more supernovae from M61 are on the way to us now, events to be detected by generations of Earth-bound astronomers yet to be born.
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