This is Spacetime Series twenty six, Episode fifty four, for broadcast on the
fifth of May twenty twenty three. Coming up on Spacetime, changing our view
of the nature of dark matter, Europe's Integral Spacecraft, Safer Last and Rocket
Labs, New Electrons Sounding Rocket, All that and more coming up on Spacetime.
Welcome to Spacetime with Stewart Garry. A new study claims that ultra lightweight
particles based on the hypothetical Axeon acting in waves could provide the answer to the
long standing mystery of dark matter. It's a disturbing fact that most of the
matter in the universe, amounting to his staggering eighty five percent by mass,
cannot be observed and consists of particles not accounted for by the standard model of
particle physics, the foundation stone upon which science is understanding of the universe is
based. What that means is that everything we see in the universe, from
the largest galaxies and stars, through the planet's asteroids, moons, right down
to the Earth. People, houses, cars, trees, dogs and cats
make up only fifteen percent of the total mass of the universe. And for
a scientist that's really disturbing. As For the other eighty five percent, scientists
refer to it as dark matter they not exist because they can see it's gravitational
influence on the things we can see. Without dark matter, galaxies would fling
apart as they rotate. But as to what dark matter is or that's the
mystery for us, it's invisible mysteries as something scientists like to solve. So
finding the particle that makes up dark matter is an urgent problem in modern physics.
Not only would it solve many problems in our current understanding of the universe,
but it would also provide a glimpse into a realm of new physics beyond
the standard model, and that is intriguing. While some theoretical models proposed the
existence of ultra massive subatomic particles as a possible candidate for dark matter, others
suggest ultra lightweight particles. Now, a report in the journal Nature Astronomy has
provided the most direct evidence yet that dark matter does not constitute ultra massive particles,
but instead comprises particles so light that they travel through space in waves.
If correct, this work could resolve an outstanding problem in astrophysics first race two
decades ago. Problem was why do models that adopt ultra massive dark matter particles
failed to correctly predict the observational position and brightnesses of multiple images of the same
galaxy created through gravitational lensing. We know dark matter does not emit, absorb,
or reflect light, which makes it difficult to observe using traditional astronomical techniques.
Today, the most powerful tool sitists have for stating dark matter is through
gravitational lensing. The phenomenon first predicted by Albert Einstein in this theory of general
relativity. Now, in this theory, mass causes space time to curve,
and that creates the appearance that light bends around massive objects such as stars,
galaxies, or groups of galaxies. Now that bending light acts like a lens,
allowing you to see clearly more distant objects. It's an important astronomical tool,
and conversely, by observing this bending of light, astronomers can infer the
presence and distribution of dark matter. Now in gravitational lensing, when the foreground
lensing object and the background lensed object, both constituting individual galaxies, are closely
aligned, modible images of the same background an object can be seen in the
sky, but the positions and brightnesses of the multiply lensed images all depends on
the distribution of dark matter in the four ground lensing object, thus providing a
especially powerful probe of dark matter. Back in the nineteen seventies, hypothetical particles
referred to as weakly interacting massive particles or whimps were proposed as the most likely
candidates for dark matter. Now, the whimps were thought to be ultra massive
that is, more than at least ten times as massive as a proton,
that they interact only with matter through the week nuclear force. The particles emerged
from supersymmetry theories, which would developed to fill deficiencies in the standard model.
However, over the past two decades, adapting ultra massive particles for dark matter
have left astrophysicists struggling to correctly reproduce the positions and brightnesses of multi lensed images.
In these studies, the density of dark matter is assumed to decrease smoothly
outwards from the centers of galaxi, in accordance with theoretical simulations employing ultra massive
particles beginning also in the nineteen seventies, but in dramatic contrast to whimps,
versions of theories that seek to rectified efficiencies in the Standard model, or those
such a string theory, which seek to unify the four fundamental forces of nature,
meaning the three in the Standard model. These strong and weak nuclear forces
and the electromagnetic force, along with gravity, have been advocating the existence of
ultra light particles referred to as axions. These hypothetical particles are predicted to be
far less massive than even the lightest particles in the Standard Model, and therefore
constitute an alternative candidate to dark matter. Now, according to the theory of
quantum mechanics, ultra light particles travel through space in waves, interfering with each
other in such large numbers as to create random fluctuations in density. These random
density fluctuations in dark matter give rise to well, I guess you call them
crinkles in space time for the dark matter surrounding galaxies. Now, you'd expect
that different patterns of spacetime around galaxies depending on whether dark matter constitute ultra massive
or ultra light particles, in other words, smooth or wrinkly, or to
give rise to different positions and brightnesses for moudibly lensed objects of background galaxies.
The new work led by Alfred Amrit from the University of Hong Kong. It's
calculated how gravitationally lensed images generated by galaxies incorporating ultra light dark matter particles would
differ from those incorporating ultra massive dark matter particles. Their research has shown that
the journal level of disagreement found between the observed and predicted positions, as well
as the brightnesses of mudibly lensed images generated by models incorporating ultra massive dark matter,
can be resolved if you simply adapt models incorporating ultra light dark matter particles.
And they also show that models incorporating ultra light dark matter particles can reproduce
the observed positions and brightnesses of multiply lensed galaxy images. Now, this is
an important achievement, revealing the crinkly rather than smooth nature of space time around
galaxies. The possibility that dark matter does not comprise ultra massive particles also alleviates
other problems in both laboratory experiments and astronomical observations. You see, laboratory experience
have been unsuccessful in finding whimsy, long favored candidate for dark matter. These
experiments are now in their final stretch. They'll culminate with the plan down experiment,
and that will leave whimps with no place to hide if they're not found.
Also, if dark matter comprises ultra massive particles, then according to cosmological
simulations, there should be hundreds of satellite galaxies surrounding our Milky Way galaxy.
However, despite intensive searches, only fifty or so satellite galaxies have ever been
discovered around the Milky Way. On the other hand, if dark matter comprised
ultra light particles instead, then the theory of quantum mechanics predicts that galaxies below
a certain mass simply can't form owing to the wave interference of these particles,
which would explain why there is a few said light galaxies around the Milky Way.
The studies authors say that incorporating ultra light rather than ultra massive particles for
dark matter resolves several long outstanding problems simultaneously, both in particle physics and in
astrophysics. It's an interesting and fascinating prospect this spacetime still to come. The
European Space Agency's Intrial Spacecraft now Safe and Rocket Labs developed a new version of
the Electron rocket, especially for use in hypersonic experiments or that and more is
still to come on spacetime. The European Space ages is Integral spacecraft is safe
at last, following an extended series of fixes developed by mission managers. The
Integral Space Observatory was designed to study some of the universe's most energetic events,
things like gamma ray bursts, black holes, and supernovae, but in twenty
twenty, the probe's thrusters suddenly failed that to keep the mission alive, these
has developed a new series of specialized maneuvers to continue flying the spacecraft using only
its reaction wheels. These are rotating gyrodigms inside the satellite that allow it to
store and use angular momentum to change its orientation. However, the spacecraft's original
safe mode system, which activates the switch off scientific instruments and rotate the spacecraft
so that its solar arrays always faced the Sun, relied on the thrusters to
spin the spacecraft safely in the event of an emergency. The safe mode it
was triggered a year later when the charge particles struck a sensitive part of intricles
electronics, disabling one of its reaction wheels and causing the spacecraft to spin away
from the Sun. Mission managers were able to override the issue and rescue the
spacecraft, but it's left the probe without a safe mode. So now Integal's
team have developed a new workaround in which newly uploaded algorithms determine the best way
for the reaction wheels to operate in order to maneuver the spacecraft during safe mode.
This is spacetime still to come rocket Lab's new Electron signing rocket variation,
and we explore the Constellation Scorpio, the spectacular M six and M seven open
star clusters, and the Etta Akwood's meteor shower produced by Halley's Comet. In
the May edition of SkyWatch, Rocket Labs developed a modified version of its highly
successful Electron orbital launch vehicle specifically designed for suborbital hypersonic test flights. Companies been
selected to provide hypersonic launch services under a Multi Service Advanced Capability Test Bed or
MACTB project, which was awarded by the United States Naval Surface Warfare Center on
behalf of the US Department of Defense and the Defense Innovation Units Hypersonic and High
Cadence Testing Capabilities or HIGHCAT program. The you modified version of the Electron to
be called the HASTE, or Hypersonic Accelerated Suborbital Test Electron, were launched from
the company's new Wallops Island Flight Facility complex on the Virginian mid Atlantic Coast.
HASTE uses the same carbon composite structure and three D printed Rutherford engines as the
electron, but with a modified kickstage for hypersonic payload deployment, a larger seven
hundred kilogram payload capacity, and custom payload fairings to accommodate larger platforms. This
space, time and time matter. Turn our eyes to the skies and check
out the celestious sphere for the month of May on SkyWatch. May is the
fifth month of the year in both the Julian and Grigorian calendars. The month
was named for the Greek goddess Mayer, who was identified with the Roman era
goddess of fertility Bernadia, whose festival was held in May. But I guess
more importantly for many of our listeners, May typically marks the start of summer
vacation season in the United States and Canada. Let's start out tour of the
night skies by looking east, where you'll see the constellations Scorpius, the scorpion
in Greek mythology, the constellation was named the Scorpius, who was sent to
Earth by the goddess Skaia in order to slay Arian the Hunter after he bursted
that he could kill all the animals on Earth. Scorpius stung Orion in the
shoulder, but Orion's life was spared by Ophiucius the Healer, and it was
placed in the heavens along with Scorpius, who continues to pursue him for eternity.
I Ran the Hunter has become the hunted forever, with Scorpius rising in
the east this time of year to triumphantly chase and defeat a Ryan who sits
in the west. Meanwhile, oh Fucius the Healer rises in the east,
following behind Scorpius to chase and crush him into the earth as the Scorpion sets
in the west. And so this ancient story continues to play out in the
heavens year after year. Interestingly, parts of the story predate the Greeks,
with Orion known in ancient Egypt as a Cyrus, the god of the underworld
and of regeneration. The brightest starr in Scorpius is Alpha Scorpie or Antarius,
a scorpion's heart in ancient Greece, and Tari's name means the equal of Mars,
the god of war. That's because it scored in orange, appearance is
very similar to that of the red planet, and also because it passes very
close to Mars every seven hundred and eighty earth days, easily seen with the
unaided eye. And Tarres is some five hundred and fifty light years away,
but it looks so bright because it's around fifty seven thousand, five hundred times
as luminous as the Sun and is one of the largest known stars in the
universe. And Tarres is a red supergiant about eighteen times the mass and eight
hundred eighty three times the diameter of the Sun. Were it placed where the
Sun is in our solar system, yielding golf, all the terrestrial planets Mercury,
Venus, Earth, and Mars, and its visible surface would extend almost
as far at as Jupiter. A light year is about ten trillion kilometers,
the distance of photon can travel in a year at three hundred thousand kilometers per
second, the speed of light in a vacuum, and the ultimate speed limit
of the universe. Astronomers believe and Harris began life around twelve million years ago
as a spectrotype ORB blue star. Astronomers describe stars in terms of spectral types,
a classification system based on temperature and characteristics. The hottest, most massive,
and most luminous stars are known as spectrotype blue stars. They're followed by
spectrotype B blue white stars, then spectralotype A white stars, spectrotype F whitish
yellow stars, spectral type G yellow stars. That's where our Sun fits in.
Then there's spectrotype K iron stars, and the coolest and least massive stars
and learn as spectrotype M red stars. Each spectral classification system can also be
subdivided using a numeric digit to represent temperature, with zero being the hottest and
nine the coolest, and then you add a Roman numeral to represent luminosity.
So put it all together and you can describe our Sun as being a G
two V or G two five yellow dwarf star, one of millions spread across
our galaxy. Also included in the stellar classification system a special types LT and
Y, which are assigned to fauled stars known as brown dwarves, some of
which were actually born at spectral type M red stars but became brown dwarves after
losing some of their mass. Brown dwarves fit into a unique category between the
largest planets, which are about thirteen times the massive Jupiter, and the smallest
spectral type M red dwarf stars, which are about seventy five to eighty times
the massive Jupiter or zero point zero eight solar masses like the similar sized red
giant battle Girls in the constellation of Ryan and Tari's Laumost certainly end its life
as a spectacular type two or cork collapse supernerva, probably sometime within the next
hundred thousand years or so. When it does explode at Lapierre as bright as
the full moon for several months on end, and will be clearly visible during
daylight hours here on Earth. And Taris has a companion star, Antari's B,
located between two hundred and twenty four and five hundred and twenty nine astronomical
units away from the primary. An astronomical unit is the average distance between the
Earth and the Sun, which is about one hundred and fifty million kilometers or
eight point three line minutes. Special analysis of Antarrees B indicates it's pulling a
lot of material off its bloated red super giant companion. Located near Antaries is
the M four globular cluster. Globular clusters are tight balls densely packed with thousands
to millions of stars which were either all originally formed at the same time from
the collapse of the same molecular gas and dust cloud, or alternatively, their
galactic centers the remains of ancient galaxies that have been merged into the Milky Way
Galaxy over billions of years. M four is composed of a million or so
stars originally born some twelve billion years ago. The M four globular cluster is
located some seven thousand, two hundred lie years away, making it one of
the nearest globular clusters to Earth. Easily seen through a pair of small binoculars,
it covers an area of the sky is seen from Earth as big as
the full moon. Astronomers estimate there are some one hundred and fifty or so
globular clusters orbiting in the halo of the Milky Way. Located near the tail
of the scorpion are two open star clusters, known as M six and M
seven. Open star clusters are loosely bound groups of a few thousand stars which
are all originally formed from the same molecular gas and dust cloud at the same
time, but are not as densely bound as globular clusters. Open clusters generally
survive for a few hundred million years, with the most massive one surviving for
maybe a few billion years now. In contrast, the far more massive globular
clusters exert fast, stronger gravitational attraction on their members, which is why they
can survive so much longer. M six, which is also known as the
butterfly cluster, is some twelve light years across and located about sixteen hundred light
years away. It contains around eighty stars, which were all less than a
hundred million years old, which is quite young in cosmic terms. The M
seven or Ptolemy cluster is named after the famous Greek astronomer a mathematician, Claudius
Ptolemy. It's about nine hundred eighty light years away, and he's far more
dispersed than him. Six, covering an area around twenty five light years across
and at around two hundred million years, it's about twice as old. Born
in the year one hundred, Ptolemay lived in Egypt while I was under Roman
rule. He wrote over a dozen scientific treaties, the first of which was
an astronomical work now known as the Almagest. While some of his works were
very insightful, much of it was error prone, and measurements were simply modified
and changed to fit his theories. He's best known for refining a geometric theory
for the universe, one which uses cycles and epicycles to place the Earth at
the center of the cosmos, with all the other bodies orbiting around it.
Unlike most ancient Greek mathematicians, Ptolema's writings never ceased to be copied and commented
upon, both in late Antiquity and in the Middle Ages. However, it's
likely that only a few truly mastered the mathematics necessary to understand his works.
That's evidenced by the many abridged and watered down introductions Totolem's astronomy that were popular
amongst the Arabs and Byzantines alike. Galileo Galilee and Isaac Newton eventually overthrew his
geocentric theory more than a thousand years later. By the way, the m
in terms like M four, M six, and M seven are abbreviations for
Messier in honor of the eighteenth century French astronomer Charles Messier, who developed an
astronomical catalog of fuzzy nebulous objects in the skies. See. Messier was a
comet hunter, and he compiled the list of one hundred and three fuzzy objects
which one commets and served from his perspective, could be ignored. Later,
other astronomers added additional celestial objects to the list, bringing the present catalog up
to one hundred and ten. Our solar system. In fact, most of
the stars we see when we look up in the night sky are located in
the Milky Way galaxies Orion Arm. The Orion Arm, also known as the
Orion Spur or the Orion Signus Arm, depending on which name you prefer,
is some three thousand, five hundred light years wide and around ten thousand light
years long. The Irian Arm is named after the Orion constellation, which is
one of the most prominent constellations in the Southern Hemisphere summer and Northern Hemisphere winter.
Some of the brightest and most famous celestial objects in the constellation include battel
Gers, Rigel, the stars of the Orion Belt, and the Orion Nebula,
all located within the Orion Arm. The Orion Arm is located between the
queen As Sagittarius Arm, which is more towards the galactic center from our position,
and the Percy's Arm, which is more towards the outer edge of the
galaxy from our point of view. The Perseus Arm is one of the two
major arms of the Milky Way, yeah, there being the Scutum Centaurus Arm
long thought of as a minus structure spur if you will, between the two
longer adjacent arms Perseus and Karna Sagittarius. Evidence was presented in mid twenty thirteen
that the Orion Arm might actually be a branch of the Perseus Arm, or
possibly a completely independent arms segment itself within the Orion arm our. Solar System,
Sun, the Earth, and all the other planets we know are located
close to the Inner Rim in what's known as the Local Bubble, about halfway
along the Orion Arms length, approximately twenty six thousand light years from the galactic
center. The Local Bubble is a cavity in the interstellar medium in the Irione
Arm, containing, among other things, the local interstellar cloud, which contains
our Solar System and the g Cloud. It's at least three hundred lights across,
and it has a neutral hydrogen density of just zero point zero five atoms
per cubic centimeter. There's just one tenth of the average for the interstellar medium
across the Milky Way, at about a six that of the local interstellar cloud.
The hot diffuse gas in the local bubble amidst X rays and is the
result of a supernova that exploded sometime during the past ten to twenty million years.
It was once thought that the most likely candidate for the remains of the
supernova was Jiminga, a pulsar and the constellation Gemini. However, later it
was suggested that multible supernova in a subgroup be one of the plats moving group
was more likely responsible becoming a rimnant supershell. Our solar system has been traveling
through this region of space occupied by the local bubble for the last five to
ten million years. Its current location is in what's known as the local interstellar
cloud, a minor region of slightly denser material within the bubble. The cloud
formed when the local bubble and another bubble called the Loop one bubble met gas
within the local interstellar cloud. As a density of about zero point three Adams
per cubic centimeter. From what we can tell, the local bubble isn't spherical.
It seems to be narrower, and the galactic plane becoming somewhat egg shaped
or elliptical, and may even become wider above and below the galactic plane becoming
shaped more like an hour glass. And it's not alone. It's abutting other
bubbles of lesser dense interstellar medium, including the Loop one Bubble. The Loop
one bubble was created by super nervy instellar winds in the Scorpius Centauris association,
some five hundred layers from the Sun. The Loop one bubble also contains the
star and taris that we spoke about earlier. Astronomers have identified several well,
I guess you'd call them tunnels, which connect the cavities of the local bubble
with that of the Loop one bubble. Collectively, they've been referred towards the
Loopers tunnel, other bubbles which are adjacent to our local bubble, and then
as the Loop two bubble and the Loop three bubble. Looks like astronomers still
have a problem when it comes to thicking up cool names. Also visible this
month is the Edder Akwards meteor shower, which is generated as the Earth passes
through the dust and debris trail left behind by Halley's comet. Comet P one
Halley's a well known short period comet which visits the Inner Solar System every seventy
five to seventy six years. The fifteen kilometer wide mountain of rock and ice
will make its next close up appearance in twenty sixty one. It's named in
honor of the British astronomer Edmund Halley, who in seventeen oh five, after
examining ancient Chinese, Babylonian and medieval European records, successfully predicted its return in
seventeen fifty eight. However, he died in seventeen forty two before his prediction
could be confirmed. The comet's highly elliptical and elongated orbit takes it from between
the orbits of Mercury and Venus out almost as far as the orbit of Pluto.
Howe's orbit is in retrograde, meaning it orbits the Sun in the opposite
direction to the planets, that is, clockwise, from above the Sun's northern
pole. This retrograde orbit results in at having one of the highest velossities relative
to the Earth of any object in the Solar System traveling at some seventy point
five six kilometus per second, or if you prefer, two hundred and fifty
four thousand and sixteen kilometers per hour. As well as the eto Achard's meteor
shower every May, Halley's comet also produces the Orionids meteor shower in Lead October.
Astronomers think Commet Halley was originally a long period comet which took thousands of
years to travel to the Inner Solar System from the Aorc Cloud, but was
gravitationally perturbed into its current orbit by close encounters with the giant outer planets.
The Orc Cloud is a hypothetical sphere of comets and asteroids beyond the heliosphere,
a mixture of vagabonds from the Solar System and objects from deep space which have
been collected by the Sun's gravitational pool. Occasionally, as the Sun passes by
another star, an Orc Cloud object will get perturbed and be flunked towards the
Inner Solar System. The Outer Akwards meteor shower runs from the nineteenth of April
through to the twenty eighth of May, peaking around me The fifth, with
around fifty five meteors an hour, making it one of the Southern Hemisphere's best
celestial showers. However, back in nineteen seventy five they were running ninety five
meteors an hour, and in nineteen eighty it was up to one hundred and
ten. Even better, the bright yellow meteors often appear as streaks known as
trains. As their name suggests, they radiate out from the direction of the
constellation Aquarius and the start at Aquary. Just look towards the east after midnight
and before dawn for the best view. Jonathan Nelly's the editor of Australian Sky
and Telescope magazine. He joins us now for the rest of our tour of
the May night skies on SkyWatch Stewart. Yeah, well, it's main hour.
So if you're lucky enough to have some nice dark skies where you live,
if you go out in the early evening, you'll see the Mookie Way
stretching all the way across the sky from the southeast to the northwest. It's
really quite a specky side if you can see it under dark skies with dark
adapted eyes. That's our galaxy, seem from the inside. It's just absolutely
glorious. The brightest star in the night sky, Serious can be seen during
May about halfway up from the western horizon. If you look out to the
western you go halfway up the sky from the horizon to overhead because it is
big bright star, and that's sirious, the brightest star in the night sky.
A little bit further, sort of down to the south, there's another
bright star. It's the second brightest star in the night sky. That's called
Canopus. And low down on the western horizon you can still make out the
shape of the constellation a Ryan above the trees or houses, whatever, or
on the horizon where you live. It's still there for only a few more
weeks. Really, it's getting very very low now. It's making its last
appearance before disappearing from view for the next six months or so. Way down
in the deep south of the sky, we've got the famous Southern Cross,
of course, which at this time of the year is nice and high,
and it's standing upright, so it looks like a sort of a kite shape,
very small kite shape. To its left, you see two bright stars
in the constellation Centaurus. Astronomers call them the two Pointers because if you draw
a line through them, it sort of points towards the Southern Cross. The
two pointers are known as Alpha and Betasentauri, and if you look at Alpha
a telescope, you'll actually see that it's two stars, and there's a third
star as well. It's some distance away and too faint to be seen through
sort of normal backyard telescopes. It's called Proximus Centauri, and Proximus Centauri is
actually the closest start of our solar system. It's a small star. It's
very dim, so you really need to know where to look for it,
and you need to have a big enough telescope. But if you just look
towards Alpha Centauri, it's roughly there. So you're looking towards the postest star
system to our star system. To the right of the Southern Cross, we've
got the constellations Karna, Vela and Puppas, which is some of my favorite
area of the sky. It's just it's just wonderful. You look. You
just get a pair of anoculars on the this and just sweep through this area.
There are star clusters and niggling things. It's just glorious because it's in
the milky way, and so there's lots of stuff to see. And yeah,
yeah, it was a big constellation called Argo Navas the ship of the
Argonauts, and got split up, and the three main constellations you've got split
into Karna, Vela and Puppas. Pappas is the poop deck, Carina is
the keel, and Vila is the sales. And there was a fourth constellation
as well. It's just nearby called Pixus, that's the compass. Would have
been a big constellation. I mean, these things look nothing like, nothing
like a ship, nothing like a sail or a poop deck or or whatever.
It's just that people decided to put their favorite ideas or mythologies or garators
that they're into the sky. So they made up their own join the dots
fares. You would not to go out and look in the sky and think,
oh, look there's a big ship. You know, the sales and
everything. So don't don't don't get full. Don't go out thinking you're going
to see something like that. Now, down in this area of the sky,
if you have dark enough skies and you've got to your eyes dark adapted,
you should be able to spot something called the Omega Centauri star cluster which
has about ten million stars in it, and it's about seventeen thousand light years
away. And there's also a galaxy down this part of the world too,
that part of the sky I should say called NGC five one two eight.
You often hear it called Centaurus A. It's about ten to fifteen million light
years away, and there's a huge galaxy. But both of these things don't
look like that to the naked eye, but you can just make them out
as a little fuzzy dots. It looks like a star that's a bit fuzzy,
and if you get some binoculars onto them that it really looks like a
fuzzy staff each of these things. And if you get telescope onto Raga Centauri
or Centaursa, they really look quite tremendous. They're really really impressive things.
So you can actually see these things with the naked eye just there's little,
tiny fuzzy blobs. They may not look impressive, but when you look at
a picture of what they really are and think, wow, my eyes are
actually seeing these things from ten million light years away. That's a huge black
hole in Centaura, say too, because it's one of the biggest radio sources
in the sky. Yeah. Look, that's why I called it NNGC five
one two eighth when I interially spoke about it, because that's its catalog name.
Pretty much everyone calls it Centaurus A these days, that Centaurus they really
refers to the radio source that is inside and just say the black hole.
Because in the very early days of radio astronomy, when astronomers are pointing these
radio tooles goes around the sky, they would find these big sources of radio
ways and they didn't really know what they were. They could pinpoint them.
It was pretty obvious that it was coming from this galaxy in this instance,
but they didn't really know what was producing these radio waves. There's Sagittarius AY,
and there's there's Cassier PA, and there's centauraus A. There's quite a
few of them like that, and as they found other ones in those constellations
called them BC whatever. So, yeah, it's an impressive galaxy. Add
and when you look at a picture taken with a big telescope or even vamited
telescopes these days, it's it's a weird looking galaxy, strange looking thing that
it's big dust laying going through the middle of it, or rather around the
outskirts of it. So this is why I say, when you go outside
and if you can spot, if you can spot, if you get a
star map and you can actually spot this thing with the naked eye. It's
just a little fuzzy blob, no brighter than a star. It doesn't look
impressive that way, but when you think that you are actually seeing this galaxy
from ten or more million light years away with your eyes, and that the
light that is coming into your eyes right now left there ten million years ago,
it's really quite incredible to its put space into perspective in it. We've
talked about Proximus Centaura, that the closest start to Earth a few moments ago,
that's only just over four light years away. Centaurus A is over ten
million light years away, So that's the sort of difference you can see just
with the naked eye. It's incredible. Anyhow, moving on, we've got
the northern half of the sky moving up to the north. Now, the
northern half of the sky from our part of the world doesn't really seem to
have many bright star fields at this time of year, at least during the
evening. There are some famous constellations there that you can see, such as
Leo, Cancer and Virgo. Leo looks quite good. Virgos just this big,
sort of seemingly empty space. But astronomers, amateur astronomers love Virgo because
when you get a telescope out and have a look into that part of space,
there are actually lots and lots of galaxies. They're too faint to be
seen with the naked eye, but a telescope can pick them up, and
they're just you're a huge galaxy cluster in the constellation Virgo. But you do
need a telescope to see them. But if you wait till after midnight,
you're going to get some spectacular constellations coming up at this time of the year,
rising over the eastern horizon. And I'm talking Sagittarius. I'm talking Scorpius,
which most people know of Scorpio and most people have heard of those two
constellations. And there's another couple called Scutum and Opayucas, which most people haven't
heard of. But that part of the Milky Way region that these constellations are
in is amazing. It's a bit like I was talking earlier about Pappas and
Villa and Karina, lots of things to see well, Sagittarius and Scorpius,
so many things to see, our star clusters of various kinds, and Nebulian
dark Nebulian star fields and things. It's just really tremendous. Even just binoculars
are good enough if you've got dark skies to have to spend hours just looking
around that part of the sky really is incredible. And you know, that's
one of the reasons why astronomy is so big in the Southern hemisphere, and
why radio astronomy in particular has been big here is because we get a good
view down here of the Sagittarius region, which is towards the center of our
galaxy. When you look towards Sagittarius, you're looking towards the center of our
galaxy. So you're looking right right into the middle of the city of stars
that we live in our galaxy. Right, So there's lots of things happening
there and lots of things for astronomous and study. Now, let's see what's
happening with the planets at the moment for this month. Venus is the main
attraction at the moment. It's nice and bright in the northwestern sky after sunset,
you really can't miss. It's because it's just big and bright. Mars
is a little bit higher than Venus and a little bit further around to the
north. It's not as bright as Venus. It's just a sort of a
medium brightness orange red sort of star. But if you take a look each
night after sunset during this month, you'll see that those two planets are seeming
to move towards each other, that the gap between them is narrowing down.
They're not actually doing that in space, of course, it's just the line
of sight effect from our vantage point here on Earth. But by the end
of June they're going to be right up closer to each other they are,
so as the next four or five, six, seven weeks go, they're
going to sort of slowly come to together in the western sky, and at
the end of June they'll be right close to each other, which max mcare
a really really good view in this month. If you go out on the
twenty fifth twenty fifth of May, you'll see that Venus and the Moon and
Mars will all be roughly roughly in a straight line at the moon in between.
So they've got Venus, the Moon, and Mars. That'll be an
easy way to identify those two planets if you're having any trouble, because you
go out and see the Moon and you think and you say, right,
oh, well, that bright star just below it, or that star and
inverted commas, the bright star below it is the planet Venus, and that
orangey red star just above them to the right, that's actually the planet Mars.
So go out on the twenty fifty fign if you've got good weather and
have a look, and you'll be able to stop them quite easily. The
other two main planets that are easy to see, Jupiter and Saturn, well
they can be found in the early morning sky, so you're gonna have to
get up early. At the start of May, Saturn is rising over the
eastern horizon just after midnight and then it's visible for the rest of the night
throught sunrise. Jupiter is coming up at about four am at the moment,
so you've got to be really a night owl or an early birds at least
to see it coming up over the horizon. If you're getting up at six
o'clock in the morning, is something that Jupiter will be some distance above the
horizon and you can't miss Jupid or either because it's it's nice and big and
bright. And if you're awake in the early hours of the morning on the
fourteenth of May, take a look outside and you'll see the Moon and Saturn
very close to each other. So if you're having trouble figuring out which one
of those things is Saturn, get outside early hours of May fourteenth and you'll
see that bright looking thing just next to the moon is Saturn. And similarly,
on the eighteenth, the Moon will have moved a little bit further along
in its orbit and then you'll have the Moon next to Jubiter. So if
you don't know which one Jupiter is, have we looked in the early morning
hours of the eighteenth and look for the moon and the bright thing right next
to it will be Jupiter. And that stupart is the sky for this month.
That's Jonathan Ally, the editor of Astray in Sky and Telescope Magazine,
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