Telescopes "on parade" at the Astrofest trade stands

I have just been to this year’s Astrofest event in London.  And I thought you might find it interesting, if I interviewed some of the traders, exhibiting at the event.

The event is a very busy couple of days for the exhibitors.  So of course, the interviews had to be done quickly, right there on the trade stands..  no quiet, controlled studio environment, for this production!  So please make allowance for the noisy, background sounds in the recordings.

I wanted to cover a variety of astronomy retailers and manufacturers.   Here are the recorded interviews I captured, for you to listen to…

Just click the “Audio MP3″ graphic, to play the audio

Astrotrac – Richard Taylor

 Download  The creator of this innovative, driven camera mount for astro-imaging, discusses current  developments.

Telescope House – David Lawrence
Download  New product offerings and telescope tips, from this large astronomy retailer.

Artemis CCD – Rui Tripa
Download Hear from the manufacturer of the Atik range of high-quality cooled CCD cameras.

Altair Astro Sky Shed Pod – Ian Knight
Download  The supplier of these low-cost, prefabricated, domed observatories. (I was impressed – I want one!)

Orion Optics – Barry Pemberton
Download  Respected British manufacturer of optical components and telescopes.

Telescope Planet – Simon Heard
Download  Retailer of a wide range of telescopes and astronomy products.

Starlight Xpress – Terry Platt
Download  Well-known manufacturer of ccd cameras for astro-imaging.

I think it’s interesting to hear from a range of businesses, all present at a single event like this.

If you enjoy a particular clip, or pick-up a useful insight, please leave a comment here.

We are familiar with occultations of the Sun and the Moon. We give these occultations a special name – eclipses – solar eclipse for the Sun and lunar eclipse for the Moon.

Lunar Eclipses

A lunar eclipse occurs when the Earth, Sun and Moon are aligned, with the Earth between the Sun and the Moon.

The Earth is three times larger in diameter than the Moon, so it easily blocks out the Sun’s light and casts a shadow on the Moon.

The Moon of course, does not produce light itself, only reflecting sunlight, so it looks dark during an eclipse.

In fact the degree of darkness does vary due to the condition of Earth’s atmosphere. If Earth’s atmosphere is clean, it will bend sunlight to some extent and this gives the Moon a slight illumination.

If however Earth’s atmosphere is dusty, as happens after major volcanic eruptions, it does not bend sunlight so much and a lunar eclipse can be a very dark one.

As the Moon orbits around the Earth once every month approximately, you might expect there to be a lunar eclipse each month, but this does not happen.

The reason is that the orbit of the Moon is inclined a few degrees to the orbit of the Earth. This ensures the Moon does not pass into the Earth’s shadow every month.

However, lunar eclipses are more often seen than solar eclipses because when they do occur, they can be seen from everywhere on Earth where the Moon can be seen at that time.

When a solar eclipses takes place, it can only be seen from a narrow strip of places on Earth. The path of totality tracks across the Earth’s surface, with a strip of partial totality on either side.

Solar Eclipses

WARNING… Never, ever look at the Sun through binoculars or a telescope, as you will certainly damage your sight. Observe an eclipse only by projecting the Sun’s image onto a sheet of card.

Solar eclipses happen when the Moon is aligned between the Sun and Earth, so that sunlight is blocked-out and a shadow is cast on the Earth.

This gives a remarkable effect here on Earth, as the Sun is obscured and then reappears some minutes later.

From a particular point on Earth, a solar eclipse is sometimes partial, and occasionally total, meaning that the Sun is completely covered by the Moon.

During a total eclipse, the Moon just about exactly covers the Sun. This is remarkable in itself.

The Moon covers the Sun in this way because the ratio of their diameters, happens to be very similar to the ratio of their distances from the Earth.

Putting it another way, the Sun and Moon have roughly the same angular size in the Earth’s sky.

This exact coverage gives rise to wonderful effects at the edge of the Sun during total eclipses such as the “diamond ring” and the “string of beads”.

It has also enabled astronomers to study phenomena very close to the Sun’s surface, such as solar prominences and the Sun’s corona.

Other Occultations

Occultations of other objects in the sky are always keenly observed and have been important to astronomers in the past.

Lunar occultations are when the Moon passes in front of a star or planet and this is interesting to observe. The Moon has no atmosphere, so stars suddenly disappear without any fading and then later, suddenly come back.

Double stars have been discovered through observing lunar occultations.

Sometimes, an star will “graze” the edge of the Moon, revealing details of hills and mountains on the Moon, as the star disappears and then reappears several times.

As recently as 1977, faint rings were discovered around the planet Uranus because a star flickered as it was occulted by Uranus.

Prior to this and going back to ancient times, only the five planets which can be seen with the unaided eye (Mercury, Venus, Mars, Jupiter and Saturn) were known.

Uranus is another “Gas Giant” and much larger than Earth, although it is smaller than Jupiter and Saturn. Uranus is about 31,000 miles in diameter at the equator, but less at the poles due to rotational flattening.

Uranus orbits around the Sun, once every 84 Earth years.

It rotates about its axis, once every 17 hours.

The axis of Uranus is uniquely (for a planet in the Solar System) tilted over at the extreme angle of 82 degrees to its orbital plane. This means that from Earth, we sometimes see a polar region and other times an equatorial region.

On Uranus, the axial tilt means that each polar area is dark for 42 Earth years, and then light for 42 Earth years!

We do not know why the axis of Uranus is tilted so much. Some people think it was the result of a huge collision, long ago.

Observing Uranus from Earth reveals no detail on the planet’s disk, even with a large telescope. It does however look blue-green in colour, due to frozen methane in the atmosphere.

Uranus’ five largest satellite moons can be seen from Earth. These are called Miranda, Ariel, Umbriel, Titania and Oberon. All are smaller than our Moon. Titania is the largest.

Uranus ring system (from Voyager)

A remarkable discovery was made in 1977, from Earth. During observation of Uranus occulting (passing in front of) a star, faint rings around the planet were suspected but not confirmed.

Then came the Voyager space probe of 1986 and the rings were clearly seen by it, as it flew past. There are 11 rings in total and they are very thin, probably less than one mile thick.

Voyager also took some remarkable images of Uranus’ satellite moons, especially Miranda which has a strange varied surface.

Uranus has a total of 21 known satellite moons.

Most people will have heard the term “constellation” and will know that it relates to patterns of stars in the sky.

Many people will probably think of astrology and the “Signs of the Zodiac”, for example Aquarius and Pisces.

But how many people know what the constellations actually are?

The star constellations are really just a fairly arbitrary way of dividing up the night sky, in a memorable way.

But arbitrary or not, the constellations are very useful and help observers to find their way around.

Dividing the sky up in this way, probably started as long ago as humankind itself.

Early people certainly drew recognisable shapes representing star patterns and also began to associate these shapes, with Gods or important legends and stories.

The constellations became somewhat more precisely defined with the early Greek astronomers, who classified a total of 48 star patterns.

At this time, the notion of the “Zodiac” stars also began. The Zodiac is the 12 star patterns or constellations, that the Sun appears to pass through, during the 12 months of the Earth year.

Hence the idea of each constellation being associated with a specific month of the year.

Interestingly, there should probably be thirteen signs in the Zodiac, because the Sun does actually pass through the constellation of Ophiuchus, as it is now defined!

There is one very important point to make about the constellations. Each constellation is not a real grouping of stars – it is only the appearance of a group, from our viewpoint here on Earth.

In fact, the stars in any particular constellation are at greatly different distances from Earth. So if we were to see them from a different position in our galaxy, they would not look like a group at all.

The constellations as astronomers know them today, were defined properly in the 1930′s, by the International Astronomical Union (IAU).

There are now 88 constellations. They vary in size, but generally, each constellation extends beyond the recognisable pattern of naked-eye stars (called an asterism) into the surrounding sky.

So for example, the constellation of Ursa Major contains the highly recognisable shape of the “Plough” or the “Big Dipper”. This is called an asterism.

The Plough asterism is made up of seven stars that appear bright to us on Earth. But the constellation of Ursa Major is much larger and contains many, many more stars and indeed other galaxies, that we can observe.

Taken together, the 88 constellations map out the entire sky into 88 areas. This is very useful to astronomers, when they want to describe where an object may be observed.

In August 2008, NASA confirmed water on the planet Mars.

They have analysed Martian soil samples gathered by the Pheonix lander, from the surface of Mars.

How is this done from so far away, you may wonder?

Astonishingly, Pheonix has a robotic arm. It is able to reach out and scoop red soil from the Martian surface, into the spacecraft’s body. There, the soil is heated and the vapours analysed.

Water has been confirmed. It has been suspected for centuries, but only now “touched and tasted” in the words of the scientists involved.

The question of water on Mars, became a full-blown controversy in the late 1800′s.

Leading astronomers notably Percival Lowell, claimed to have observed networks of “canals”, through telescopes. Previously, they had been suggested by Shiaparelli and termed “canali”.

Quickly, it was speculated they were the work of intelligent beings – hence the notion of “Life on Mars”. Water is a prerequisite for life as we know it.

In 1898, the publication of H G Wells’ famous novel “The War of the Worlds”, added populist fuel to the debate.

Perhaps this latest discovery from NASA of water evidence, will rekindle the speculation? I’m sure, further work is needed for any proof.

Neptune is the furthest out of the “Gas Giant” planets and is right out at the limits of our Solar System, 2800 million miles from the Sun.

The story of its discovery is fascinating…

Neptune

Neptune’s existence was suspected long before it was actually discovered.

Astronomers in the early 1800′s found that they could not reconcile the observed position of the newly discovered planet Uranus, with the position they expected through calculations.

So some astronomers began to suggest that perhaps there was an undiscovered planet in the same area of the Solar System, that was affecting the orbit of Uranus.

Various people became involved in the search for the new planet. Notably, these included a young French mathematician called Urbain Le Verrier and a young English mathematician called John Couch Adams.

Both of these men calculated where in the sky, they would expect Neptune to be found. Adams did not publish his work, but Le Verrier did by means of two notes, in 1845 and 1846.

The search to find Neptune observationally began.

John Challis, Professor of Astronomy at Cambridge, used the Northumberland 11.6 inch refractor but did not find it.

(Incidentally, this telescope can be visited and is still used at the present time, in Cambridge. I have seen it and it is a wonderful piece of astronomy history)

Reviewing the episode later, after the new planet had been discovered, Challis found that he had actually seen and recorded Neptune almost immediately in the predicted position, but he had not realised it. I bet he was cross!

Meanwhile, Le Verrier had sent his calculations and predictions to Johann Galle at the Berlin Observatory.

With this valuable information, Galle looked and found very quickly. Neptune was discovered on his first night’s observation in 1846.

Later, it was discovered that Adams had also been correct with his predictions of Neptune’s position, but unfortunately, it had just taken too long for the English astronomers to follow it through to the observation stage.

Neptune is not actually that difficult to see with a telescope, if you know where to look and what you are looking for.

Through a telescope, the Neptune’s disk looks blue. Like Uranus, this is due to light absorption by methane.

Neptune is also very similar in size to Uranus.

The largest of Neptune’s moons, Triton was discovered soon after the planet itself in 1849, but the second moon, Nereid, took much longer (1949). It is close to the planet and hard to see.

The most significant recent event was the Voyager space mission. It flew past Neptune in 1989.

Voyager found six additional satellite moons, together with a faint ring system – another similarity with Uranus.

However Neptune does not share Uranus’ extreme axial tilt. Neptune’s axis is inclined at just 29 degrees to the plane of the orbit. Only a few degrees more tilted than Earth.

Voyager also succeeded in measuring the period of rotation. Neptune’s “day” was found to be 16 hours 7 minutes long.