Thursday, 3 April 2025

A little ramble through Apus the Bird of Paradise

 Stars in the southern hemisphere were of course unknown to European astronomers because no one had travelled there before the 1400s. This is why most of the constellations in this part of the sky are referred to as modern constellations.

One example is Apus the Bird of Paradise which unfortunately like many of these modern constellations contains few if any bright stars. Johann Bayer called the constellation Apus Indica the Indian Bird. That title has been dropped today and it is just referred to as Apus.

Apus is what is called a circumpolar southern hemisphere constellation, this means that from countries like Australia and New Zealand it can be seen all year around. This is much like the familiar group of stars we call the Plough which can be seen all year from countries such as Britain and is called a northern circumpolar constellation.

This constellation is best seen in July which of course in the southern hemisphere is during the winter.

Apus the bird of paradise was introduced to the sky in the 1590s by the Dutch astronomer and cartographer Petrus Plancius from the observations of Dutch navigators Pieter Keyser and Frederick Houtman, when they voyaged to the southern hemisphere and visited countries such as Indonesia or what at that time was known as the Dutch East Indies.

Plancius had produced in 1589 a celestial globe using what information was available regarding the southern stars. These included constellations such as Crux the Southern Cross and Triangulum Australe the Southern Triangle as well as the Magellanic Clouds which were called Nubecula Major and Minor. These were reported by the Portuguese explorer Ferdinand Magellan c 1480-1521 as he journeyed around the world. These we know today are nearby Large and Small Magellanic Clouds which are nearby galaxies to our own Milky Way Galaxy.

Plancius knew that the Dutch navigators Pieter Keyser and Frederick Houtman would be travelling to the southern hemisphere so he met them and trained them to draw and note features in the sky so he could replicate them on a new star globe he was producing. With the knowledge that Keyser and Houtman provided Plancius in either 1597 or early 1598 produced a new celestial globe with an additional 12 constellations. None of these can be seen from Britain and they describe mostly animals and subjects that travellers of the day had seen as they explored the southern hemisphere.

The name of the constellation is derived from the Greek word apous, which means “footless.” (Birds of paradise were at one point in history believed to lack feet). The Greater Bird of Paradise known in India had a magnificent white, yellow and red plumage but unsightly legs, which were cut off by the natives desiring to offer the white man only the attractive part of the bird. There are no myths associated with the constellation.

In China the constellation was referred to as E Cho the Curious Sparrow or the Little Wonder Bird.


Apus is located near the south pole star, there are no bright stars in Apus, the brightest are alpha at magnitude 3.8 and is around 430 light years away. The sky must be clear and dark to see this star.  It is a K class giant star with a surface temperature of around 4,000 degrees it is cooler than the Sun.

Apus is an example of a constellation where using Johann Bayer’s Greek alphabet sequence does not work. This is because the second brightest star is gamma with a magnitude of 3.9 compared to the brightness of beta which is magnitude 4.2.

Although the Milky Way flows through Apus there are no bright clusters of stars to be seen. The brightest is NGC 6101 a globular cluster lying around 50,000 light years away. However, at magnitude 9.2 a telescope would be needed to see it.


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Wednesday, 2 April 2025

Moon above Mars on April 5th

 After passing close to Jupiter a couple of days ago the Moon can be seen just below Mars on April 4th and on April 5th it will be just above Mars which is in the constellation of Gemini the twins. Mars is near  Pollux and Castor the two brightest stars in Gemini.



Last night April 1st it was possible to see Earthshine on the Moon this is when light from the Sun is reflected from the Earth onto the Moon and we can see the dark ghostly outline of the unlit part of the Moon, you might be able to see it again tonight.



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Tuesday, 1 April 2025

April 1st is the 65th anniversary of first weather satellite Tiros 1

 Weather is always a major talking point between people, it can be hot, cold, wet or dry. 

 We are also used to getting fantastic images beamed done from weather satellites orbiting the Earth showing just what the weather is going to be including incredible pictures of hurricanes from space. 

Did you know that all these modern satellites can trace their time lines back to TIROS 1 the first weather satellite which was launched on April 1st 1960. TIROS stands for Television Infrared Observation Satellites 

TIROS 1 was an experimental weather satellite built by NASA and would operate until June 1960 when an electoral fault occurred and the probe failed. 

 Although the pictures it sent back are poor by the standards of today it showed what could be done to help people predict the weather today.


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Monday, 31 March 2025

The Astronomy Show on Drystone Radio

 Join me, Martin Lunn MBE tonight and every Monday evening from 7.00 pm-9.00 pm on the award-winning Astronomy Show on Drystone Radio, probably the only regular astronomy show on any radio station in the country. 

I will take my weekly look at the night sky and look at all the latest news in astronomy. There will be the astronomical anniversaries this week plus the latest news from the astronomical societies in the north of England.

 


The Astronomy Show every Monday evening only on Drystone Radio live online at www.drystoneradio.com DAB radio in Bradford and East Lancashire, or 102 and 103.5 FM and can also be heard later on the Drystone Radio Podcast.

The Moon and Jupiter, April 2nd and 3rd

 The crescent Moon will be dancing with the largest planet in the solar system Jupiter again this month. On April 2nd the crescent moon can be seen to the side of Jupiter in the western sky. 



This serenade will continue because on the following night, April 3rd the Moon will have glided past Jupiter and can be seen above the planet.


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Sunday, 30 March 2025

A little ramble through Antlia the Air Pump

 The first of our modern constellations Antlia the Air Pump, and I am afraid it is a very poor example of a constellation as many of the modern ones are. When astronomers refer to modern constellations, they are referring to ones that were created in the 1500s, 1600, or 1700s, compared to what is referred to as classical constellations which have existed for several thousand years.

In theory Antlia can be seen from Britain very low in the sky during spring evenings but as there are no bright stars it is difficult to find.

We owe the formation of this constellation to the French astronomer Abbe Nicolaus de la Caille (1713-1762) who is frequently encountered in connection with certain constellations in the southern sky. He travelled to the Cape of Good Hope in 1750 to chart the southern heavens and in 1763 produced a catalogue of over 10,000 stars which was published posthumously. The catalogue itself was very important it’s just a shame that most of his constellations were not.

He would introduce 14 new constellations to the sky, all in the southern sky and sadly they are all faint and obscure groups and many of them represent what were at the time modern instruments. I can understand why he was trying to promote these new scientific inventions; it is such a shame that the constellations he produced were not bright and spectacular and do not reflect the true scientific importance of the scientific instruments. Antlia was originally called Machine Pneumatique.

With this being a modern constellation there are no myths or legends associated with it.

There were originally 48 constellations the number has now increased to 88 many of these modern constellations are made up of faint stars just to fill in the gaps between the main constellations. Many do have modern sounding names. Abbe Nicolaus de la Caille is guilty of this.

The air pump was created to honour Robert Boyle’s invention of the air pump around 1660.


Antlia can be seen very low in the sky during spring evenings from Britain however there are no bright stars in the constellation, you would need a very clear southern horizon and a very clear sky to be in with a chance of seeing any stars in Antlia. To locate Antila you would need to look below the constellation of the Hydra which is itself a faint constellation. I remember when I lived in the south of England, I did look for the stars of Antlia a few times, but I never saw any.

The brightest star, alpha has magnitude or brightness of only 4.2 the star has no name and is hardly visible to the naked eye even under the best of conditions. It is a K class giant star meaning that it is cooler than the Sun. It is 320 light years away. The other stars in Antlia are even fainter.

Even from the southern hemisphere where it is naturally much higher in the sky there is little to remark about Antlia. If you observed from the southern hemisphere where in theory it is easier to see, the sky will have to be clear any mist or moonlight or light pollution would make Antlia impossible to see.

Antlia is an example of one of these faint and quite irrelevant constellations which if it was removed from the star maps and its stars were transferred to nearby classical constellations no one would notice. However, it has survived all the changes to the lists of constellations over the centuries and was included in the list of constellations defined in 1930 by the International Astronomical Union. This means that you can still find Antlia on all-star charts.

 


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Saturday, 29 March 2025

James Nasmyth and his 1858 Thomas Cooke telescope

 

 James Nasmyth 1808-1890 Scottish engineer, philosopher and inventor of the Steam Hammer was also very interested in astronomy and when he retired from business in 1856 he moved to Penshurst in Kent to follow his hobby of astronomy. 

In 1858 he purchased an 8 inch Cooke and Sons telescope which was complete in every respect possible. The telescope cost £600.  Today that would be over £95,000


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