Skynotes: August 2020
From the depths of mid-winter in the southern hemisphere here's a (warming) look in ultraviolet of the Sun, the source of all our heat and light.
Up close with the Sun
There are several missions studying our local star but two are our special interest this month; NASA’s Solar Dynamics Observatory (SDO) and the ultra-close ESA/NASA Solar Orbiter.
Read our article The Sun like you’ve never seen before for images, an amazing time lapse video, and more.
Melbourne sun times
| Date | Rise / Solar noon* / Set (day length) |
|---|---|
| 1st | 7.20am / 12.26pm / 5.33pm (10.12 hrs) |
| 11th | 7.09am / 12.25pm / 5.41pm (10.31 hrs) |
| 21st | 6.57am / 12.23pm / 5.49pm (10.52 hrs) |
| 31st | 6.43am / 12.20pm / 5.58pm (11.15 hrs) |
*When the Sun is at its highest crossing the meridian or local longitude.
Moon phases
| Phase | Date |
|---|---|
| Full Moon | Tuesday 4th |
| Third Quarter | Wednesday 12th |
| New Moon | Wednesday 19th |
| First Quarter | Wednesday 26th |
This month’s Moon apogee (furthest from Earth) is on Sun 9th at 404,659 km and perigee (closest to Earth) is on Fri 21st at 363,513 km.
Planets
Mercury is not visible this month as it is too close to the sun.
Venus ‘the morning star’ rises in the east around 4am but will be lost in the early morning light by 7am.
Mars can be seen in the east from about 11pm reaching its highest elevation around 4am as it moves across to the north-west before fading from view by 7am.
Jupiter is bright from 6pm high in the east and moves to its highest position about 10pm in the north before setting in the west around 4.30am.
Saturn can be seen from about 6.30pm as it follows Jupiter. It rises to its highest point 10:30pm in the north and then sets in the west around 5am.
Meteors
The major meteor shower this month is the Perseids which peaks on the 13-14th. This is a strong Northern Hemisphere shower with around 100 meteors predicted per hour. The shower appears in the northern constellation of Perseus and is difficult to view from the southern hemisphere. Perseids are fast, bright and frequently leave persistent trails. They appear to come from a point below the north-east horizon. This shower is associated with Comet Swift-Tuttle which passed near the Sun in 1991 leaving a trail of particles for the Earth to regularly pass through.
Stars and constellations
Crux, or the Southern Cross, is high in the south-west. On a clear, moonless night it may be possible to see beside it the Coal Sack nebula, a dark region of dust that blocks light from more distant stars. Look on the side leading to the nearby Pointers (Alpha and Beta Centauri). In some aboriginal stories the Coal Sack is the head of a giant emu, Tchingal. The Pointers are its long neck, and larger dark clouds along the Milky Way form its body and legs that stretch all the way to Scorpius. For more on First Peoples’ astronomy visit the Australian Indigenous Astronomy website.
Low in the southern sky are the bright stars Achernar (to the east) and Canopus (to the west). These stars lie opposite the Southern Cross and never disappear below the horizon.
High in the east after sunset and moving overhead during the night is the spectacular curving line of stars of Scorpius with a central star in its body being the red giant star Antares. Below and following during the night is Sagittarius the centaur-archer whose bow and arrow also forms the ‘Teapot’ (you can imagine tea pouring into Scorpio’s curving tail).
International Space Station
ISS orbits every 90 minutes at an average distance of 400 km appearing like a bright star moving slowly across the night sky. Here are some of the brightest passes expected this month over Melbourne and Central Victoria:
Morning
- Saturday 8th: 6.43am–6.49am, South-West to North-East
- Tuesday 11th: 5.57am-6.02am, West-South-West to North-East
Evening
- Wednesday 19th: 7.25pm-7.29pm, North-West to South
- Thursday 20th: 6.37pm-6.43pm, North-West to East-South-East
For predictions go to the Heavens-Above website.
On this day
3rd 2004, the MESSENGER (USA) mission to Mercury was launched.
4th 2007, Phoenix (USA) Mars lander was launched.
5th 1998, NASA Near Earth Object Program is created to detect and catalogue asteroids that approach Earth.
5th 1939, first person to walk on the moon, American Neil Armstrong, is born.
6th 2012, the Mars rover Curiosity lands on the red planet.
6th 1996, a meteorite from Mars discovered in Antarctica is said by NASA to contain possible microfossils of bacteria.
7th 1959, Discoverer 1 (USA) returns the first satellite images of the Earth.
10th 1675, Royal Greenwich Observatory is established east of London.
10th 1990, Magellan (USA) arrives at Venus and begins radar mapping of its surface.
12th 1877, Astronomer Asaph Hall at the US Naval Observatory discovers Mars’ tracks are clearly eviden.t 12.6km diameter moon Deimos.
12th 1898, Eros, the first near-Earth asteroid is found by Carl Gustav Witt.
17th 1970, Soviet probe Venera 7 is launched to Venus and will send first pictures from the surface of another planet after landing on December 15th.
18th 1877, Mars’ 22.5km diameter moon Phobos is discovered by Asaph Hall.
18th 1868, new element ‘helium’ is found by Pierre Janssen from analysis of the Sun’s spectrum. It is now known to be the second most abundant element in the universe after hydrogen.
19th 1960, two dogs, Belka and Strelka, are launched aboard Sputnik 5 (USSR), and successfully returned to Earth.
19th 1646, birth first Astronomer Royal John Flamsteed who catalogued 3000 starts.
20th 1975, launch of Viking 1 (USA), first probe to land on and study Mars.
20th 1977, Voyager 2 (USA) launched to the planets of the outer Solar System.
22nd 1989, Voyager 2 (USA) discovers positive evidence for Neptune’s rings.
24th 2006, first formal definition of ‘planet’ is debated and vote upon by International Astronomical Union in Prague resulting in dwarf planet status for Pluto.
25th 1609, Galileo demonstrates to the Venetian Doge and officials his improved version of the newly invented telescope.
31st 1913, birth of famous British radio-astronomer Bernard Lovell.