August 2019: Small Steps

In the show this time, we talk to Jonathan Pober about his work with 21cm line and understanding galaxy formation and cosmology, George Bendo rounds up the latest news, and we find out what we can see in the August night sky from Ian Morison, Haritina Mogosanu and Samuel Leske.

The News

This month in the news: Protests over the thirty metre telescope in Hawaii and the 50th anniversary of the Apollo moon landing.

On the Big Island of Hawaii, opponents of the construction of the Thirty Meter Telescope (TMT) have physically blockaded the Mauna Kea access road, which allows people to travel to the observatories at the top of Mauna Kea. This is the latest in a series of protests that have taken place regarding the construction of the TMT as well as the operation and construction of other telescopes on the mountain.

To review, Mauna Kea is currently considered to be the best observing site in the Northern Hemisphere. Because the mountain is both broad and tall, the airflow over the top of the mountain is laminar rather than turbulent. This means that optical and near-infrared light from stars is blurred very little by the atmosphere, allowing astronomers to produce sharper images. Additionally, the summit is above an atmospheric inversion layer that forms nightly on the Big Island and that traps moisture at lower altitudes. As a result, the air at the top of the mountain is very dry, which is particularly ideal for submillimetre observations.

However, Mauna Kea has a unique ecosystem and multiple prehistorical and cultural sites, and opponents of the development of Mauna Kea are generally concerned about these sites. Aside from the summit itself, the most important high-altitude sites are Lake Waiau, which is an unusual high-altitude lake, and the adze quarries where prehistoric Hawaiians acquired unusually dense volcanic rocks for making stone tools. Moreover, many people currently go to the summit for modern-day Hawaiian spiritual practices. Opponents of Mauna Kea development are not only worried about the destruction of the pristine landscape but have also pointed to poor stewardship of the site by the University of Hawaii, which has been primarily responsible for the management of the site. The complaints include issues with the removal of trash and old equipment and reports of multiple chemical spills, although most such spills were indoors and did not harm the environment.

The TMT specifically has been targeted with multiple protests and lawsuits since Mauna Kea was selected as the site for the observatory in 2009. Construction was initially meant to start in 2015, but in a lawsuit filed by opponents, the construction permit was revoked because the process for issuing the permit was not followed correctly.

After re-applying for a building permit and clearing other lawsuits, approval was given to the TMT to start construction the week of the 15th of July. However, protesters blockaded the Mauna Kea access road on 13th of July before construction could start. Crowds of thousands of people appeared at the site. For safety reasons, the other observatories on the mountain decided to suspend all operations and order all employees and researchers to evacuate the mountain.

The protests have led to a number of events and controversies. Early during the protests, police arrested and then released 38 people at the site, many of whom were described by the protestors as kupuna, the Hawaiian term for spiritual leaders. A tropical storm at the beginning of August disrupted the protests, although a core group remained at the site. At a meeting of the Board of Regents for the University of Hawaii, opponents of Mauna Kea development called for the resignation of the president of the University of Hawaii, and the university's board of regents has approved the formation of an action group to investigate the current management of the mountain. Multiple celebrities have also visited the protesters to show their support, most notably actors Dwayne Johnson and Jason Momoa.

Having said all of this, the protests have largely been peaceful so far. However, no end to the protests is currently in sight.

In less controversial news, people in July celebrated the 50th anniversary of the first Apollo Moon Landing. The landing took place on the 20th of June 1969 and was the most notable events in the history of manned space exploration. This prompted many different events from across the world, including a reunion of people involved in the Apollo 11 mission at the Kennedy Space Center. Jodrell Bank Observatory scheduled the Bluedot music festival this year to coincide with the anniversary, and to mark the occasion, many of the events at Bluedot were Moon-themed. This anniversary has provided impetus to new projects to return to the Moon, particularly NASA's Artemis program, which has the goal of eventually building up a permanent presence on the Moon, and it will also provide support for China's and India's Moon exploration programs.

Interview with Jonathan Pober

Jonathan talks about his work with 21cm line and understanding galaxy formation and cosmology. He talks about the challenges and triumphs of characterizing the 21cm signals using the SKA phase telescopes.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during August 2019.

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

The Planets

• Jupiter, starts the month shining at magnitude -2.5 which increases to to -2.6 as the month progresses. At the same time, its angular size increases from 43 to 46 arc seconds. As May begins it rises by midnight UT so will be due south around 3 am UT whilst at month's end it rises at ~9:30 pm UT so due south at ~01:30 UT. See the highlights fro when the Great Red Spot faces the Earth. Sadly it is heading towards the southernmost part of the ecliptic and currently lies in the southern part of Ophiuchus just above Scorpius so, as it crosses the meridian, it will only have an elevation of ~ 14 degrees. It lies just above the centre of the Milky Way. Atmospheric dispersion will thus take its toll and an atmospheric dispersion corrector would greatly help to improve our views of the giant planet.
  
  
• Saturn, shining with a magnitude increasing from +0.5 to +0.3 during the month, rises around midnight during the month so crosses the meridian just before dawn. Its disk is ~18 arc seconds across and its rings - which are still nicely tilted from the line of sight - spanning 40 arc seconds across. Morning twilight is the best time to observe it but, sadly, now in Sagittarius and lying on the southern side of the milky way, it is at the lowest point of the ecliptic and will only reach an elevation of ~10 degrees. As with Jupiter, an atmospheric dispersion corrector will help improve our view.
  
  
• Mercury, passes through superior conjunction (behind the Sun) on May 21st and will only be visible, low in the west-northwest, on the last few days of the month. One will need a very low horizon and binoculars could well be needed to reduce the Sun's background glare, but please do not use them until after the Sun has set.
  
  
• Mars, though fading from +1.6 to +1.8 magnitudes during the month, is still visible in Taurus in the south western sky after sunset lying half way between Betelgeuse, in Orion, and Capella, in Auriga. Mars sets some three hours after the Sun at the start of May (with an elevation as darkness falls of ~20 degrees) but less than two and a half hours by month's end. Its angular size falls from 4.2 arc seconds to less than 4 arc seconds during the month so one will not be able to spot any details on its salmon-pink surface.
  
  
• Venus, has a magnitude of -3.8 in May with its angular size reducing from 11.5 to 10.8 arc seconds during the month as it moves away from the Earth. However, at the same time, the percentage illuminated disk (its phase) increases from 88% to 92% - which is why the brightness remains constant at 3.8 magnitudes. It rises about an hour before the Sunbut its elevation is only ~4 degrees at sunrise so a very low horizon in the East is required and binoculars may well be needed to spot it through the Sun's glare - but please do not use them after the Sun has risen.
  
  

Highlights

• May 7th - after sunset: Mars lies above a thin crescent Moon. Given a low horizon looking towards the west after sunset one should, if clear, be able to spot Mars lying halfway between Betelgeuse and Capella above a very thin crescent Moon. .
  
  
• April 12th - evening: The Moon in Leo Looking southwest in the evening a first quarter Moon will be seen lying close to Regulus in Leo.
  
  
• May 19th - early evening: Mars above M35 in Gemini. Looking west in early evening if clear, and using binoculars or a small telescope one could see Mars lying just above the open cluster, M35, in Gemini. Perhaps a last chance to see Mars at the very end of its apparition.
  
  
• May20th - midnight: Jupiter and the Moon. During the night of the 20 May, Jupiter will lie over to the right of the waning gibbous Moon.
  
  
• May 23rd - early morning: Saturn and the Moon. In the early Morning of the 23rd of May, Saturn will lie up to the right of the waning gibbous Moon.
  
  
• May 28th - around midnight: spot asteroid 1, Ceres. On the 28th May, Ceres is at its closest approach to Earth lying over to the right of Jupiter. It will have a magnitude of 7 so binoculars should enable you to spot it and the chart will help you find it. A planetarium program such as Stellarium will show you its position in the days before and after its closest approach. Ceres is the largest of the minor planets and is now classified as a 'Dwarf Planet'.
  
  

Southern Hemisphere

Haritina Mogosanu and Samuel Leske from the Carter Science Centre in New Zealand speak about the Southern Hemisphere night sky during August 2019.

• The rise of the GalaxyKia Ora from New Zealand, we are here at Space Place at Carter Observatory holding Galactic Conversations from the heart of Wellington in the Southern Hemisphere, with the music of the amazing Rhian Sheehan, our Wellingtonian star composer. This month we have a very special guest, one of our own Milky Way Kiwi - from far across the Cook Strait and The Southern Alps, from Lake Tekapo - Holly. We have again instructions for looking up, we talk a little bit about the month of May we look at what the Sun is up to, the Milky Way, Orion and Scorpius, we talk about the brightest stars visible and finally some favourite binocular and telescope objects, circumpolar objects and planets.
  
  
• A bit about May is the fifth month of the year in the Julian and Gregorian Calendars a month of spring in the Northern Hemisphere and autumn in the Southern Hemisphere. It is named after the Greek goddess, Maia or Roman goddess of fertility, Bona Dea. Old English - Maius, Latin name - Maius mensis - Month of Maia, Old French - Mai. Maia was one of the Pleiades and the mother of Hermes. Maia is the daughter of Atlas and Pleione the Oceanid and is the oldest of the seven Pleiades. Because they were daughters of Atlas, they were also called the Atlantides. For the Romans, it embodied the concept of growth and as her name was thought to be related to the comparative adjective maius, maior "larger, greater". Convallaria majalis, the Lily of the Valley, one of my favourite flowers - is named after it and it is the flower of May in Europe.
  
  
• What’s the Sun up to? The Sun rises from 7 to 7:30AM throughout the month and sets from around 5:30 to 5:00 PM. Beautiful and long nights are here.In May, the Sun transits first the zodiacal constellations of the Ram (Aries) and after 14th of May is in Taurus. This means that Scorpius is on the other side of the zodiacal wheel and visible starting after sunset.
  
  
• The Milky WayWe are now looking towards the centre of our galaxy, which rises in the South East just after sunset and reaches meridian after 3 AM at the beginning of the month and 2 am towards the end.
  
  
• Bright stars in the Milky WayStarting from the West after sunset is Betlegeuse, then in zig-zag to the North is Procyon, the Little Dog alpha star. Zig-zaging again and is Sirius, and Adhara, in the Big Dog, and Suhail al Muhlif and Avior in Vela, the beautiful stars of the Southern Cross, the two pointers, Alpha and Beta Centauri then later on in the night after the centre of the Milky Way rises, is Antares and Shaula in Scorpius, Nunki in Sagittarius and last but not least, after midnight, Altair and last but not least, Vega grazing the northern horizon.
  
  
• Orion and Scorpius. Orion is very close to Taurus and it will sink further towards the horizon as the month progresses. Enjoy it while it lasts, for the rest of this month.
  
  
• Bright stars on the eclipticThen Regulus in Leo (which is extremely close to the ecliptic) then Spica, the blue giant in Virgo, Zubenelgenubi, another star grazing the ecliptic and Zubeneschamali just beneath it. Zubenelgenubi means the northern claw and Zubeneschamali the southern claw, alluding to these two stars that have been the claws of Scorpius before they were chopped off and turned into the current constellation of Libra. They are followed by Antares which is the last very bright star visible on the ecliptic before sunrise.
  
  
• Circumpolar Objects to New Zealand The beautiful Southern Cross and the pointers are high in the sky. Gacrux and Acrux are crossing the meridian around 10 PM at the beginning of the month and just after 8PM at the end of it. Omega Centauri is in a great position to observe, as well as Musca, Vela, Carina and their Diamond Cross, and False Cross and the Large Magellanic Cloud and its Tarantula Nebula
  
  
• Binocular Objects in MayLower down, Omega Centauri, is a globular cluster in Centaurus and in Scorpius, there are the Butterfly Cluster, M7 open cluster and NGC6231 open cluster.
  
  
• Telescope Objects in MayA fantastic night in central wellington where the large magellanic cloud is only visible with averted vision, still, not bad for a capital city. We looked at the Southern Beehive NGC 2516, Gem Cluster NGC 3293, Southern Pleiades IC 2602, Wishing Well NGC 3532, Jewel Box NGC 4755, Omicron Velorum IC 2391, Omega Centauri NGC 5139, Alpha Centauri and Acrux, Tarantula NGC 2070.
  
  
• Planets Jupiter is in the sky just after 7:30 followed by Saturn two hours later and Venus is in the morning sky.
  
  
• Clear skies from New Zealand.
  
  

Odds and Ends

The Tibet Air Shower Gamma Experiment has announced the first ever detection of photons with an energy above 100 teraelectronvolt (TeV) coming from an astrophysical source. This Cherenkov telescope, which observes muons showering down on the earth as a result of extremely high-frequency light interacting with the atmosphere, has found 24 photons above 100 TeV coming from the Crab nebula. The Crab nebula is a supernova remnant about 2 kiloparsec away in the Taurus constellation. It is unclear how these photons are produced.

Late last year the KAGRA experiment in Japan was tested at cryogenic temperatures for the first time. An article by the team submitted this January and published this July details their work. The experiment is similar in concept to LIGO, it is an attempt to detect gravitational waves using the same principle of the difference between two laser beams sent out along arms kilometres in length. KAGRA has two major features to improve our knowledge in gravitational waves: it is underground to reduce the effects of seismic vibrations and the mirrors are cryogenically cooled to reduce the effects of thermal expansion and contraction on the mirrors used. The research concludes that the cryogenic system worked, cooling the mirrors to around 20K over the course of 35 days, and that alignment of the mirrors is achievable at these temperatures. The authors conclude by claiming the first scientific run of the experiment will be conducted in late 2019.

Recently, Wendy Freedman and her team from the University of Chicago found a new way to measure the expansion rate of the universe, also called the Hubble constant. Measurements of the Hubble constant have historically been contradictory to one another. The value recently derived from observations of Cepheid variables, for instance, is in a tension with that measured by studying the Cosmic Microwave Background. The new value, obtained by comparing the distance values of red giant starts to the apparent recessional velocity of target galaxies, sits inbetween those two measurements. The tension is not broken, and may require a new model of physics to resolve.

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