ikenbot:

Best Telescopes for Beginners: Reviews & Buying Guide

I get the question “What’s the best telescope for amateurs” a lot on both the CWL and Scinerds blog, so I figured I would hand the ball over to the experts on the answer. Here’s an awesome feature from Space.com detailing what the best telescopes for beginners are, how to find the right scope to fit your needs, and all you need to know about what telescope you decide to choose.

Thanks to digitally driven manufacturing and low-cost onboard microelectronics, it’s now quite practical to own a telescope of very high quality and amazing capability. And there’s a lot of startling star-stuff within easy reach of these innovative instruments.

Telescope Types:

There are four basic telescope types that are good for beginners: Reflector, Refractor, Hybrid and Dobsonian. Let me show you a first-rate example of each:

Reflector Telescopes: Celestron NexStar 130SLT Review

Among the best reflector telescopes for beginners, Celestron’s NexStar 130SLT boasts big aperture, respectable optics and easy set-up with the Sky Align Go-To computer.

Refractor Telescope: Meade StarNavigator 102 Review

Low maintenance, excellent optical quality, a fine Go-To computer and the capability of daytime use for targets on Earth persuaded our reviewers to name Meade’s StarNavigator 102 the best refracting telescope for beginners of 2012.

Hybrid Telescope: Celestron NexStar 4SE Review

Compact size, innovative light-path and beefy mount got our reviewers’ attention. Celestron’s NexStar 4SE is one of the best hybrid telescopes for beginners, with a database of 40,000 celestial objects and daytime spotting scope capability.

Dobsonian Telescope: Orion StarBlast6i Review

Big light-gulping aperture and simple intuitive operation give Orion’s StarBlast 6i a strong edge among low-price Dobsonian telescopes for neo-astronomers. There are no motors to drive it but the “IntelliScope” computer helps you find targets.

Which one is right for you?

To decide which type you might want; think about where you live, where you might go, and how you’ll be observing. All four will work for the night sky. But, if you intend to also bird-watch – or people–watch! – you’ll probably want either a Refractor or a Hybrid, because the image you’ll see can be “right-side-up” and easy to track when it moves.

Also, think about maintenance. Refractors and Hybrids are closed tubes; they accumulate little dust on the optics. Reflectors and Dobsonians do take in a little dirt. But, they’re easy enough to clean. And, because air can easily circulate through, they adapt (“equilibrate”) to changing temperatures faster. That’s important to keep image distortion low.

Reflectors and Dobsonians also require that you manually “collimate” their mirrors from time to time. That’s not hard to do, but you still have to do it. Hybrids rarely need collimation. And Refractors never do.

Aperture

Aperture means “opening.” In telescope-speak, it refers to the size (diameter) of the useable part of the main mirror or primary lens. If all else is equal, wider aperture gives you sharper focus and brighter images. A telescope’s main job is actually not to magnify, but to funnel photons into your eyeball so your brain can assemble a picture. So, basically, bigger is better.

Computer Control

All the beginner telescopes we’ll show you have simple on-board computers to help you point at celestial targets. These will save you time and effort. You won’t have to learn how to read star charts right away, or struggle to find objects in the ever-changing night sky. But these units do require that you set them up properly to track accurately.

Now. some astronomers will disagree with our decision to include such “go-to” computers in the beginner category. They believe you’d be better off buying “more telescope” for the price.

We hear and respect that viewpoint. In a perfect world, you COULD devote long hours to learning the sky prior to observing. But we believe you’ll be more likely to invest that study-time AFTER you’ve had some early successes experiencing the wonders of the cosmos.

Getting started

For a quick start, dive into these four short articles and videos on best examples of telescope types for beginners:

Reflector: Newton Astride A Tripod

Hybrid: Compact Power & Cool Design

Refractor: Galileo’s Elegant Simplicity

Dobsonian: A Universe For Every Person

If you’d like a deeply detailed look into this rewarding hobby, please read Joe Rao’s extensive article: “Telescopes - What You Must Know.”

And, if you just want to see the detailed specs of each one, click through these:

Reflector: Celestron NextStar 130 SLT

Hybrid: Celestron NexStar 4SE

Refractor: Meade StarNavigator 102

Dobsonian: Orion StarBlast6i

[Full Article]

ikenbot:

New Research Confirms The Existence of Dark Matter

Image: Don Dixon

Fans of dark matter can rest easy. A study published last month raised eyebrows by suggesting that our cosmic neighbourhood is empty of the extra mass needed to hold the galaxy together. But a re-analysis shows that the dark matter was there all along.

Dark matter is the mysterious, invisible stuff that makes up 83 per cent of the matter in the universe. It is responsible for keeping galaxies from flying apart despite their high spinning speeds, and has aided our understanding of how structures in the universe formed.

The most popular theories say that dark matter is a hitherto undetected particle called a WIMP (weakly interacting massive particle) that is shy of interacting with ordinary matter through any force except gravity.

But several underground detectors waiting for WIMPs have come up empty, or with conflicting results. If the galaxy is so full of dark matter, why hasn’t it shown up yet?

In April, a team led by Christian Moni-Bidin of the University of Concepcion in Chile thought they had a solution: the WIMPs aren’t actually there.

The team tracked the motions of more than 400 stars within 13,000 light years of Earth to estimate the mass of matter – visible and dark – in the sun’s local neighbourhood. They concluded that the mass they found could be explained by the visible matter alone, with no need for dark matter.

But the team made a subtle error, say Jo Bovy and Scott Tremaine of the Institute for Advanced Study in Princeton, New Jersey.

Moni-Bidin and colleagues considered stars whose orbits take them far above or below the Milky Way’s main bright disc, and used the speed at which they orbit the centre of the galaxy to figure out how much of a pull they feel from the nearby mass of stars and dark matter. They assumed that the stars’ speeds would be the same no matter how far they were from the galactic centre. Observations of dust clumps have shown that this assumption is true for young stars orbiting in the galactic disc, which mostly move in a near-perfect circle.

But the stars that orbit high above or far below the disc can’t have circular orbits, Bovy says. The only stars that reach such great heights have been kicked away from the disc by matter in the galaxy’s spiral arms, which sent them on highly elliptical orbits.

Full Article: Crisis averted: Dark matter was there all along