VirtualAstro, Author at Universe Today

August 12, 2011April 26, 2016 by VirtualAstro

Enjoy the Perseid Meteor Shower Even if it’s Cloudy

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Oh no! You have planned to go out and watch the peak of the Perseid Meteor Shower this weekend, but it’s cloudy. You can’t see a thing!

Don’t despair, as you can still enjoy the meteor shower in other ways, until the sky clears.

There are few possibilities and two rely on reflections of radio signals from distant sources, such as TV transmitters many hundreds of miles away.

You can “listen” to meteors with Spaceweather Radio.

Or you can “watch” a visual graph is with the Meteorscan Meteor Live View created at the Norman Lockyer observatory in Devon England

How do these work? Basically these transmitters are at a distance where they are beneath the horizon from the radio receivers perspective. If you tune into this far of transmitter all you would normally get is static as it is so far away and hidden, due to being below the horizon.

When a meteor strikes Earth’s atmosphere it decelerates rapidly. The friction created by the air causes the meteor to burn up at extremely high temperatures creating the white “shooting star” that we are all familiar with. This process also ionizes the air along the trail making it possible to reflect radio waves.

The reflected signals are picked up by the radio receiver and can be heard as pings or whistles. Data can also be displayed on a computer in the form of different types of graph.

There will also be a live audio and video stream, along with a live “Stay Up All Night” chat about the Perseids with NASA astronomer Bill Cooke and his team from the Marshall Space Flight Center as they answer your questions about the Perseids via live Web chat. Join them on Friday, Aug. 12 at 11 p.m. EDT — 03:00 UTC GMT — then make plans to stay “up all night” until 5:00 a.m. EDT on Saturday, Aug. 13.

Of course, as we have mentioned before, you can join in with watching the Perseids with the rest of the world via Twitter and the #Meteorwatch hashtag. Even if you can’t see any meteors, you can see where other people are watching them with the Twitter Meteor Map

Check out all these fantastic and interesting meteor tools and hopefully you’ll have a chance to go out and enjoy the shower with your eyes when the sky clears.

August 11, 2011December 24, 2015 by VirtualAstro

How To Enjoy The 2011 Perseid Meteor Shower

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It’s time for the Perseid Meteor Shower and you want to bag some meteors (shooting stars), but how? Maybe you just want to know where and what time to look, or perhaps you are having a Perseid party and you want everyone to have a great time.

If so, then please read on…

First, you don’t need a telescope or binoculars or any high tech equipment. You just need your own eyes and glasses if you wear them.

It’s a good idea to be away from bright lights and if possible have a red light torch or red flashlight, but most importantly try to get your eyes adapted to the dark.

Bright light will instantaneously ruin dark adaption so shining flashlights into faces is a big no-no and looking directly at the Moon isn’t going to help either. Position yourself so you don’t get the Moon in your view.

The Perseids don’t rain down out of the sky; they appear every few minutes and this year, you may only see the rarer bright ones and very bright fireballs due to the full Moon that will be up, and the glare it will unfortunately provide. But if you can get in a good position to avoid the glare, sit back and wait to see some meteors. This is totally worth the wait, but you need to be comfortable or you will give up, go indoors and not see any.

The best bet is to get a reclining garden chair or airbed or something similar to lay back and relax upon. Lots of people put those yard trampolines to very good use and use them as meteor observing platforms.

Dress warmly and cover yourself with blankets or a sleeping bag, August is a summer month, but it can get quite chilly at 1:00am and this will make you give up early too, so stay warm.

Have plenty of drinks and snacks ready so you can basically camp out and not have to keep on getting up, or doing things, because this is when you will, ironically, miss the best fireball of the evening.

Fireball Meteor — Perseid fireball. Image Credit: Pierre Martin of Arnprior, Ontario, Canada.

Where do I look and what direction?

This is the most common question I hear people ask about meteor showers and the answer is very simple.

Follow the above comfort guidelines, look up and away from the Moon and fill your gaze with the sky.

Perseid meteors originate from a fixed point in the sky called the radiant, which is in the constellation of Perseus, however meteors will appear in any part of the sky. You can trace their paths back to the radiant.

After midnight, look towards the East/Northeast part of the your sky to find Perseus. To find it look for the easily identifiable constellation Cassiopeia, the big “W” in sky! Perseus is just below Cassiopeia.

You can draw, take pictures and even video the Perseids, but the simplest and most enjoyable thing is to lay back, relax and be patient and you will be rewarded with a great a view.

The best times to look will be in the dark pre-dawn sky on August 11, 12 and 13, 2011.

You can also follow along with Universe Today and Meteorwatch.org with #meteorwatch on twitter. Ask questions, see what others are seeing, share your experiences and images using the hashtag #meteorwatch

Most of all, enjoy your Perseid experience and have fun!

August 11, 2011December 24, 2015 by VirtualAstro

The Perseids: Why is There a Meteor Shower?

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Every year from late July to mid-August, the Earth encounters a trail of debris left behind from the tail of a comet named Swift-Tuttle. This isn’t the only trail of debris the Earth encounters throughout the year, but it might be one of the most notorious as it is responsible for the annual Perseid meteor shower, one of the best and well-known yearly meteor showers.

Comet Swift-Tuttle is a very long way away from us right now, but when it last visited this part of the Solar system, it left behind a stream of debris made up of particles of dust and rock from the comet’s tail.

Earth encounters this debris field for a few weeks, reaching the densest part on the 11th to 13th August.

The tiny specs of dust and rock collide with the Earth’s atmosphere, entering at speeds ranging from 11 km/sec (25,000 mph), to 72 km/sec (160,000 mph). They are instantly vaporised, emitting bright streaks of light. These tiny particles are referred to as meteors or for the more romantic, shooting stars.

The reason the meteor shower is called the Perseid, is because the point of the sky or radiant where the meteors appear to originate from is in the constellation of Perseus, hence Perseid.

When the Perseid meteor shower reaches its peak, up to 100 meteors an hour can be seen under ideal dark sky conditions, but in 2011 this will be greatly reduced due to a full Moon at this time. Many of the fainter meteors (shooting stars) will be lost to the glare of the Moon, but do not despair as some Perseids are bright fireballs made from larger pieces of debris, that can be golf ball size or larger.

These amazingly bright meteors can last for a few seconds and can be the brightest thing in the sky. They are very dramatic and beautiful, and seeing one can be the highlight of your Perseid observing experience.

So while expectations may be low for the Perseids this year, keep an eye out for the bright ones and the fireballs. You will not be disappointed, even if you only see one!

Join in on twitter with a worldwide event with Universe Today and Meteorwatch.org just follow along using the hashtag #meteorwatch ask questions, post images, enjoy and share your Perseid Meteor Shower experience.

August 6, 2011December 24, 2015 by VirtualAstro

Recent Active Sun Prompts Stunning Auroras Over England

Aurora over Cumbria 5/6th August 2011 Credit: Raymond Gilchrist

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On the evening of the 5th of August 2011 the Aurora Borealis, Northern Lights were seen as far South as Southern England! At approximately 18:00 Universal Time (19:00 BST) the Earth’s magnetosphere was hit by a coronal mass ejection from the sun, triggering a powerful geomagnetic storm and Aurora.

This storm measured 8 on the K index (aurora richter scale) which ranges from 0 – 9 so this was a big storm.

It is quite common to see Aurora in Northern Scotland, but at approximately midnight, aurora was seen as far south as Berkshire, Wiltshire and Hampshire in Southern England. It is incredibly rare to see aurora this far south — the last time I remember was in 2003.

I was incredibly lucky to briefly see the pale greenish hue of the aurora through clouds from my back garden in West Berkshire.

Unfortunately a lot of people in England and Scotland were under thick cloud and missed this fantastic display, but thanks to fantastic astrophotographers such as Raymond Gilchrist (@RayGil on twitter) we are able to see the aurora through his images.

Did you see any aurora activity in your location? Geomagnetic activity remains high as I write this article, so I hope the sky clears and we are given another fantastic display of this rare phenomenon soon.

Aurora on the River Tay, Newburgh, Fife, Scotland Credit: photosbyzoe

June 30, 2011December 24, 2015 by VirtualAstro

Noctilucent Clouds and A Bright Northern Star

Noctilucent Cloud display with the bright star Capella over West Berkshire UK Credit: Adrian West

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Noctilucent Clouds are finally here! Well, at least they were for me at about 3:00am on the 29th of June.

I have heard that there have been some sightings, but for me, this mornings display heralds the new NLC season – a month later than usual?

Conditions were amazingly warm, and the night was still and magical as I looked northwards from my home in West Berkshire UK. I couldn’t help but notice a burning bright star almost due North and quite low, Capella in the constellation of Auriga! This is when I spotted the first faint wisps of noctilucent cloud.

Capella isn’t always in the North, but it is this time of year and it usually makes a guest appearance during morning noctilucent cloud displays.

Noctilucent clouds are very rare and tenuous clouds on the edge of space and occur at altitudes of around 76 to 85 kilometers (47 to 53 miles).

They are only seen when conditions are just right (still not fully understood) after sunset or before sunrise. They are illuminated by the sun, which is still way below the horizon from the observers location. Due to their very delicate nature, noctilucent clouds can only be seen at these times. More info on what NLC’s are, can be found here

Will you see any NLC’s?

Noctilucent clouds over Saimaa. Credit: Wikipedia

June 20, 2011December 24, 2015 by VirtualAstro

June 21 ATV Re-Entry: A Man-Made Fireball In The Sky

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The Johannes Kepler ATV (Automated Transfer Vehicle) has undocked from the International Space station and will re- enter Earth’s atmosphere on June 21st ending its mission in fiery destruction.

The ATV has been docked with the ISS since February, where it delivered supplies, acted as a giant waste disposal and boosted the orbit of the International Space Station with its engines.

The X-wing ATV delivered approximately 7 tonnes of supplies to the station and will be leaving with 1,200kg of waste bags, including unwanted hardware.

The Johannes Kepler ATV-2 approaches the International Space Station. Docking of the two spacecraft occurred on Feb. 24, 2011. Credit: NASA

On June 21st at 17:07 GMT the craft will fire its engines and begin its suicide mission, tumbling and burning up as a bright manmade fireball over the Pacific Ocean. Any leftover debris will strike the surface of the Pacific ocean at 20:50 GMT.

During the ATV’s re-entry and destruction there will be a prototype onboard flight recorder (Black Box) transmitting data to Iridium satellites, as some aspects of a controlled destructive entry are still not well known.

ESA says that this area is used for controlled reentries of spacecraft because it is uninhabited and outside shipping lanes and airplane routes. Extensive analysis by ESA specialists will ensure that the trajectory stays within safe limits.

There still are some chances to see the ISS and Johannes Kepler ATV passing over tonight, but if you in a location where you can see the south Pacific skies starting at about 20:00 GMT, keep an eye out for a glorious manmade fireball.

A shower of debris results as the ATV continues its plunge through the atmosphere. Credit: ESA

The longest day – Summer Solstice 21st June 2011

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June 21st, 2011 is Summer Solstice – the longest day of the year.

This is the time when the Sun is at its highest or most northerly point in the sky in the Northern Hemisphere and when we receive the most hours of daylight. If you live in the Southern Hemisphere it is the reverse, so you will be having “Winter Solstice.”

Also known as “Midsummer” the Summer Solstice gets its name from the Latin for sol (sun) and sistere (to stand still). The Sun reaches its most Northerly point and momentarily stands still before starting its journey South in the sky again until it reaches its most Southerly point “Winter Solstice”, before repeating the cycle. This is basically how we get our seasons.

It’s not actually the Sun that moves North or South over the seasons although it may appear so. It’s the Earths axial tilt that causes the Sun to change position in the sky as the Earth orbits the Sun throughout the year.

Why Are There Seasons — The angle of the Sun and the Earth's seasons. Image credit: NASA

Summer Solstice/ Midsummer is steeped in ancient folklore especially in Northern Europe with the most famous place directly related to it being Stonehenge, where the sun has been worshiped for thousands of years.

The Sun reaches its most Northerly point in the sky at 17:16 UTC momentarily and from that point forward starts to make its way South. This means the days will get shorter and shorter until Winter Solstice in December.

June 14, 2011December 24, 2015 by VirtualAstro

Why Can We See Multiple ISS Passes Right Now?

Four ISS passes over the UK last night. Credit: Mark Humpage

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Last night in the UK, US and Europe, we were spoiled with multiple and bright ISS passes. Not just one or two, but up to six passes were able to be viewed throughout the evening in some locations.

This is quite rare as normally we get only one or maybe two visible passes in the evening or morning.

So why are we getting as many as four to six passes per night?

The ISS did receive an orbital boost and its altitude increased by around 20 kilometers. The orbital height of the ISS has an effect on how many visible passes there are at present in the Northern hemisphere. Another reason is because of the time of year.

We are only a week or so away from the Summer Solstice, the time of year when the Northern hemisphere receives the most hours of sunlight. Naturally this means we only have a few hours of darkness and the further North you go, the shorter the nights are and in some locations this time of year, it doesn’t ever get truly dark.

So why does this affect the ISS?

Basically the ISS visible passes have increased due to the station being illuminated much more by the Sun as there are more hours of sunlight right now, but the effect will wear off when we pass through Summer solstice and the nights get longer again.

Take advantage of this rare time and go outside and enjoy the ISS as much as you can in this series of visible passes.

Need to know how and when you can see the ISS? NASA has a Skywatch page where you can find your specific city to look for satellite sighting info.

Spaceweather.com, has a Satellite Tracker Tool. Just put in your zip code (good for the US and Canada) to find out what satellites will be flying over your house.

Heaven’s Above also has a city search, but also you can input your exact latitude and longitude for exact sighting information, helpful if you live out in the country.

June 3, 2011December 24, 2015 by VirtualAstro

Supernova Discovered in M51 The Whirlpool Galaxy

A new supernova (exploding star) has been discovered in the famous Whirlpool Galaxy, M51.

M51, The Whirlpool galaxy is a galaxy found in the constellation of Canes Venatici, very near the star Alkaid in the handle of the saucepan asterism of the big dipper. Easily found with binoculars or a small telescope.

The discovery was made on June 2nd by French astronomers and the supernova is reported to be around magnitude 14. More information (In French) can be found here or translated version here.

Image by BBC Sky at Night Presenter Pete Lawrence

The supernova will be quite tricky to spot visually and you may need a good sized dobsonian or similar telescope to spot it, but it will be a easy target for those interested in astro imaging.

The whirlpool galaxy was the first galaxy discovered with a spiral structure and is one of the most recognisable and famous objects in the sky.

May 27, 2011December 24, 2015 by VirtualAstro

Beginner’s Guide to Astronomy – Refractor Telescopes

If you ask someone to describe or draw a telescope, nine times out of ten it will be a refractor.

The refractor telescope is quite possibly the most common or easily recognized telescope. It is a very simple design, which has been around for hundreds of years.

The history of the refractor is that it was first invented in the Netherlands in 1608, and is credited to 3 individuals; Hans Lippershey, Zacharias Janssen – spectacle-makers and Jacob Metius.

In 1609 Galileo Galilei heard about the refracting telescope and made his own design, publically announcing his invention and further developing it through extensive experimentation. Galileo’s friend Johannes Kepler further experimented with the design, introducing convex lenses at both ends, improving the operation of the telescope.

Many advances were made and the refracting telescope became the primary instrument for astronomical observations, but there was one problem; they were huge and some were many tens of feet long!

But now, after more than 400 years and — luckily — through advances in know-how and technology, the refractor has become much more powerful and compact than some of the behemoths in the early days.

Refractors or refracting telescopes employ a simple optical system comprising of a hollow tube with a large primary or “objective lens” at one end, which refracts light collected by the objective lens and bends light rays to make them converge at a focal point.

Light waves which enter at an angle converge on the focal plane. It is the combination of both which form an image that is further refracted and magnified by a secondary lens which is actually the eyepiece. Different eyepieces give different magnifications.

The larger the size of the objective or primary lens = more light gathered. So a 6 inch refractor gathers more light than a 2 inch one. This means more detail can be seen.

There are two main types of refractor telescopes: “Chromatic” – entry level and upwards with 2 lens elements and “Apochromatic” – premium, advanced and expert level telescopes with 3 or more very high quality lens elements with exotic mixes of materials.

Chromatic refractor telescopes are particularly good for observing bright objects such as the moon, planets and resolving things like double stars, but many astronomers who image deep sky and other objects use very high quality apochromatic refractors, due to their superior optics.

Refractor telescopes are very low maintenance due to being a sealed system and it is a simple case of setup and enjoy, without the fiddling lengthy setup times you may get with other telescopes.

Refractors give clean and crisp views due to the sealed nature, unlike other telescopes like Newtonians which are subject to cooling and air turbulence issues.

Due to their small size they are very portable and can also be used for terrestrial observations the same as binoculars, which are basically two refractors bolted together.