Description

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere's night sky during February 2019.

The Planets

• Jupiter, starts the month rising around 3:30 a.m. and brightens from magnitude -1.9 to -2.0 as the month progresses whilst its angular size increases slightly from 33.6 to 36.1 arc seconds. By month's end it rises by ~2 am so will be higher in the sky before dawn. Sadly it is heading towards the southern part of the ecliptic and currently lies in the southern part of Ophiuchus just above Scorpius.
  
• Saturn, shining with a magnitude of +0.6, rises one and a half hours before the Sun at the start of the month some 85 minutes after Venus. Its disk is ~16 arc seconds across and its rings - which are still 24 degrees from the line of sight - spanning 35 arc seconds across.
  
• Mercury, passed through Superior conjunction (behind the Sun) at the end of January and will not become visible in the evening twilight until around the 12th of the month having a magnitude of -1.2. During March's second half it dims to magnitude -0.2 but, by its end, sets some one and a half hours after the Sun. Mercury, with an angular size of 7 arc seconds, reaches its greatest elongation east on the 26th of the month, then 18 degrees away from the Sun and with an elevation of ~9 degrees 45 minutes after the Sun has set. Binoculars could well be needed to reduce the background glare, but please do not use them after the Sun has risen.
  
• Mars, though fading from +0.9 to +1.2 magnitudes during the month, remains prominent in the south western sky after sunset at an elevation of ~38 degrees after sunset as it moves north-eastwards from the constellation of Pisces into Aries on the 12th of the month. (If only it could have been at this elevation when at closest approach last year!) Its angular size falls from 6 arc seconds to less than 5 and a half arc seconds during the month so one will not be able to spot any details on its salmon-pink surface.
  
• Venus, begins February with a magnitude of -4.3. as it Its angular size reduces from 19 to 16 arc seconds during the month as it moves away from the Earth but, at the same time, the percentage illuminated disk (its phase) increases from 62% to 72% - which is why the brightness only reduces from -4.3 to -4.1 magnitudes. See the highlight above when it lies close to Saturn.
  

Highlights

• February 9th - before dawn: Jupiter, Venus and Saturn. Looking southeast before dawn one should, if clear, be able to easily spot Jupiter lying up to the right of Venus and, just above the horizon, Saturn. A low horizon in this direction will be needed to see Saturn.
  
• February 10th - evening: Mars above a waxing Moon. Looking southwest in the evening if clear, Mars will be seen lying above a waxing crescent Moon. Uranus lies to the upper left of Mars.
  
• February 11-13th - evening: Mars skirts past Uranus. Looking southwest in these evenings if clear, Mars (magnitude 1) will be seen passing close by Uranus giving us an easy way of finding the magnitude 6 planet.
  
• February 16th - just before dawn: Venus and Saturn close by. If clear just before dawn, and given a low horizon towards the southeast, one should be able to see Venus lying just up to the right of Saturn. Jupiter shines to their upper right.
  
• February 22nd - just after sunset: Mercury above the western horizon. If clear just after sunset, and given a low horizon towards the west, one should be able to spot Mercury. Binoculars might be needed to cut through the Sun's glare, but please do not use them until after the Sun has set.
  
• February 28th - before dawn: three planets and a waning crescent Moon. If clear before dawn, and given a low horizon towards the south southeast, one should be able to observe what will be the best skyscape of the month with Venus, Saturn, a waning crescent Moon and Jupiter forming a line above the horizon.
  
• February 13th and 25th: The Alpine Valley. These are two good nights to observe an interesting feature on the Moon if you have a small telescope. Close to the limb is the Appenine mountain chain that marks the edge of Mare Imbrium. Towards the upper end you should see the cleft across them called the Alpine valley. It is about 7 miles wide and 79 miles long. As shown in the image is a thin rill runs along its length which is quite a challenge to observe. The dark crater Plato will also be visible nearby. You may also see the shadow cast by the mountain Mons Piton lying not far away in Mare Imbrium. This is a very interesting region of the Moon!
  

Southern Hemisphere

Haritina Mogosanu and Samuel Leske tell us what we can see in the southern hemisphere's night sky during February 2019.


• Kia Ora from New Zealand, hi everyone, we are here at Space Place at Carter Observatory in New Zealand holding Galactic Conversations from the heart of Wellington in the Southern Hemisphere, my favourite place to be, with the music of the amazing Rhian Sheehan, our Wellingtonian star composer. I'm Haritina Mogosanu, and I'm Samuel Leske. At this time of the year we are looking towards the edge of our galaxy, the Milky Way, and Orion is just like last month, the main feature out there in the sky apart from the south celestial objects.
  
• Sun Rise. Everybody talks about the evening night sky but I'd love to also mention the wonderful early riser.
  What's an early riser? I think it is someone who wakes up around 4am and then commutes to work, or they are just a morning person. At that time of the morning, about 4am, the galactic centre rises as well, not just the people getting up early. And as they rise, Jupiter is out there in Ophiuchus about 30 degrees above horizon and above it is the red giant Antares. As each day goes past, Venus will seem to lower towards the Eastern horizon towards Saturn, which will also be visible in the early morning, around the 19 of February, when it will have a spectacular conjunction with Venus.
  
So a most interesting morning sky in February and let's just add that the Southern Cross will be high up in the sky at that early hour, crossing the meridian and pointing straight south so at least South is easy to find at 4AM in the morning if you misplaced your car keys or train pass.
Mars is still the only planet in the evening sky that is visible with the naked eye and the Sun sets around 8:30 and is in the constellation of Capricornus going into Aquarius from the 16h of February. The brightest, second brightest and third brightest stars are visible in one shot in the evening sky: Sirius, Canopus and Alpha Centauri.
Last month we talked about Orion and some of the objects from the Northern Hemisphere that sit below Orion in the Southern Sky, such as the fabulous Rosette Nebula and the elusive M74 and the Magellanic clouds. We also talked gastronomy, about the pot and the frying pan. This month, in February we will continue that conversation as we do some more star hopping.

• Star Hopping. is an ancient stargazing technique that involves hopping from one star to the next and making patterns and paths on the way.
  
Let's get hopping.

I say we start at sunset, and here in Wellington Mars is very low in the sky on the Western horizon. All the other planets are in the morning sky as we mentioned, so if you are a morning person you're in for a treat.
Two ancient royal stars are flanking Mars. To the left of Mars is Fomalhaut, bright star, 19th brightest at a magnitude of 1.16. To the right of Mars almost at the same altitude maybe just a bit higher and roughly the same distance as Fomalhaut is the star cluster the Hyades and the bright star Aldebaran. This is another one of the four royal stars, which also include Regulus and Antares, visible in the morning sky. In between Aldebaran and Mars, at the same height as Mars is the Pleiades.

For Maori, they are now called Te Tawhiti, the Shining Ones. They are in the constellation Taurus which is just bordering the Milky Way. On the other side of the barely visible Milky Way, remember we are looking towards the edge of our galaxy, the celestial twins Castor and Pollux are the just grazing the horizon. Straight up from Pollux (which is the highest in the sky here) is Procyon, the mini-dog star or hot dog as we call it here at Space Place as the asterism is made of two stars so that's what we came up with. I know this one from Frank Andrews, the father of good planetarium presentations here in Wellington.

• Gastronomy. So in the spirit of gastronomy - this one is from him as well, we will now point out The Pot. Higher up in the sky from Procyon is Orion, upside down here to what is known in the Northern hemisphere. So the red giant Betelgeuse is lower and then comes Orion's belt, the sword and then Rigel, the blue giant is up the top. Now when you look towards Orion, you're looking towards The Pot. Its handle is made up of Orion's sword and the bottom is Orion's belt. Holding the shape of the pot is Eta Orionis, a variable blue white main sequence double star in Orion between 3.4 and 4.9 magnitude.
  
We are very practical people here in New Zealand, and it is summertime and when you think of all that seafood that we will point out later, it is very nice to be here, there's just the little issue that the nights are too short at this time of the year.

• Are you Sirius? Yes very much so, Sirius is to the right of Orion and in a straight line up from Procyon, if you look northeast. And if you draw a line from Procyon to Sirius around 9PM in the middle of the month it will point to Zenith the point straight overhead.
  
To the right of the Zenith and almost as high, is my favourite Cat Star, Canopus, also I've heard of this from Frank, he explained to me that any serious astronomer in New Zealand has a ginger cat called Canopus. This is the tradition about the Cat star. Canopus is part of Carina, a spectacular zone in the sky.
We cover more in detail the part of the sky between Sirius and Canopus in our How to Find series, Navigating the Night Sky on Milky Way Kiwi, Part 3.
Also in Carina is Eta Carinae the famous fabulous hypergiant and another variable double star. Eta Carinae was the competition for Canopus, because due to a great outburst, in the 1840's it became the second brightest star in the sky. Eta Carinae is one telescope field to the left of the Southern Pleiades cluster, which is at the bottom of the Diamond Cross and almost halfway in between the Southern Cross and the False Cross. Again we cover a lot of detail in our Navigating the Night Sky, Part 4, where we have precise instructions for Southern Pleiades, Eta Carinae nebula, Pearl Cluster, NGC 3532 and the Jewel Box Cluster. And you will only need binoculars for these ones.
So all we had to do was to follow the Milky Way to south - or for those of us who cannot see the Milky Way all the time due to light pollution, we have followed the brightest stars and objects in the sky, hopping from Mars to the Pleiades and the Hyades, Procyon, Orion, Sirius, Canopus and now we arrive at the south celestial circle of stars. If you do see the Milky Way (lucky you) then as it lowers towards the southern horizon you can see the False Cross, then lower down, the Diamond Cross and then the famous Southern Cross. Both the Southern Cross and the two pointer stars, Alpha and Beta Centauri are in the Milky Way, roughly in the direction of south. All of these crosses are made up of circumpolar stars and turn around what we call South Celestial Circle so you will find them at different hours being at different heights in the sky.

• Asterisms and fish. The stars from Centaurus, Alpha and Beta Centauri (Hadar) together with Birdun, Muhlifain and Delta Centauri make the South Celestial Frying Pan. This is a season -based asterism visible probably best in January and February. Southern Cross and the Coalsack are respectively the Fish and the Flounder (the latter is the Maori name for the Coalsack) in the frying pan.
  
If you imagine that the Southern Cross is a big arrowhead, on the other side of the 60 degrees declination South circle is Achernar the end of the river Eridanus. These are the most prominent stars of the early evening sky, if we can call that evening, as we can only start seeing them after 8:30 when the Sun sets here this month.
And is really awesome to see as the Sun goes down, Fomalhaut is the bright star right above it. I used to watch that one from the Northern hemisphere dreaming of the southern sky. And one of the first things I've learned about the sky in the Northern Hemisphere is that Fomalhaut shows the secret passage way to south to the initiate. I kept wondering why that is until I came here to Wellington and you can see further to the left of Fomalhaut, maybe just slightly higher in the sky is Alpha Centauri triple star system, our closest neighbour, the third brightest star in the sky.
cross / arrowhead that points at Achernar, the end of the river Eridanus, about 50 degrees high in the sky.
And so the story goes if you put one hand on the southern cross and one hand on Achernar, and clap, that's very near the south celestial pole - the extension of the south pole in the sky and then drop down to the horizon and you've found south.

• Canopus. It's an amazing sky this month, even though we don't see much of the Milky Way, we have brilliant stars in the sky. Sirius is the brightest star in the night sky, Canopus is the second brightest and Alpha Centauri is the third brightest star at about 4 and a quarter light years away. Sirius, a double star is also very close to us, about 8.60 light years, whereas Canopus, also known as Alpha Carinae is about 309 light years away. And perhaps not too many people know but Canopus is also a double star.
  
I really love this star, my favourite thing about it is that it's used by interplanetary spacecraft as a reference point since it lies away from the plane of our solar system where the bright planets are found. And also in my favourite book, Dune the planet Arrakis is the third planet orbiting Canopus.
We don't know if there's any spice orbiting around Canopus but we can tell it's a great star anyway. Even though it appears half the brightness of Sirius, Canopus is a rare F0 class supergiant star. These stars are rare and poorly understood, they can be either evolving to or from a red giant. And that made it difficult to understand the absolute brightness of Canopus, which help us get some idea of the distance to it.
Only with the launch of the Hipparcos satellite were we able to tell it's about 310 light years from Earth, as estimates before that gave anything between 96 to 1200 light years. So at 310 light years away Canopus is about 15, 000 times brighter than our Sun. It's so big that compared to our Sun it stretches about three quarters of the way across Mercury's orbit. Canopus is post main sequence as it has ceased fusing hydrogen in its core.

• Eta Carinae. If Canopus is a supergiant, which we all thought that was awesome, well, Eta Carinae is a hypergiant. Eta Carinae has the highest confirmed mass and luminosity of any star that has been studied in detail, and is a candidate to become a supernova or even a hypernova - so it will be seen by our neighbours in others galaxies when it goes off. Eta Carinae is 7,500 light years away .
  
We will end here next to the biggest star known, Eta Carinae pondering about how big is big.
In the meantime, we look forward to seeing you at Space Place.

• Space Place and Telescopes. Space Place is one of the historical icons of New Zealand in terms of astronomy, located at the heart of our capital city. We have amazing historical telescopes, a 23 cm Cooke built in 1867 that we use for public viewing and we also have a retro Boller and Chivens 16 - I noticed that's the word used now when people talk about stuff made in the 60's.
  
The Cooke has quite a story behind it and how it got to New Zealand and eventually how it ended up in Wellington. It has been a very important telescope for research including being used to photograph Halley's Comet in 1910. Also on display is a James Short telescope. We only look at this one - and not through, it's locked in the displays, it's a very important telescope we believe came here with Captain Cook and it was donated by Adam Read, he is the son of Peter Read who was the creator and presenter of the New Zealand's Night Sky TV show in 1960's.
We also have a beautiful planetarium where I spend a lot of my time.
If you ever wish to find us, Space Place is at the top of the botanic gardens looking out to the harbour, and surrounded by flowers and New Zealand birds that are amazing and especially now in the summertime it is a poetry for the senses.

• I am Haritina Mogosanu and I am Samuel Leske, and we are Milky Way Kiwi at Space Place at Carter Observatory in New Zealand, Southern Hemisphere, with the February podcast, the Southern Hemisphere section for the Jodcast.
  
Thank you and Clear skies from Wellington!