The Earth, in its speedy inner orbit, swung between the Sun and Uranus last week.  On Oct 19, 2017 Uranus reached opposition which implies that we are about as close to Uranus as we get and so it appears somewhat larger and brighter.   It is a good time to get a glimpse of Uranus, especially  with the weather forecast calling for a few nights with clear skies.

Uranus’ current location is in the constellation Pisces and is positioned due south around midnight PDT.  Uranus is dim with a magnitude of 5.7 and is barely visible with naked eyes and then only from a very dark site.   It is visible with binoculars or small telescope but appears small with an apparent diameter of just 4.1 arc-seconds.  At higher magnifications, you might notice its disc-shape and its blue-green tint.  Don’t expect to see surface features on the ice giant;. Even giant professional telescopes can barely do that.

Originally Thought to be a Comet

William Herschel discovered Uranus in England on the night of March 13, 1781.  At first Herschel thought it was a comet, but it was confirmed as a planet several years later. Herschel tried to have his discovery named “Georgia Sidus” after King George III. Astronomer Johann Bode suggested naming it after the Greek deity Ouranos.

Its Cold There

Uranus is much closer to the Sun than Neptune but the minimum temperature on Uranus (-224 degrees C) is colder than Neptune, making Uranus the coldest planet in the solar system.

Lots of Dim Moons

Uranus has 27 known moons to date, five of which can be observed from earth. Only, the four largest are visible in amateur instruments. Ariel, Umbreil, Titania, and Oberson are all dimmer than 14th magnitude but may be visible in telescopes larger than 10 inches. The moons of Uranus are named after characters in the the works of Shakespeare and Alexander Pope.

 

Long Days on a Titled Planet

Uranus nearly lies on its side with a tilt of about 98 degrees. Uranus completes a single rotation on its axis in about 17 hours. But the tilt of Uranus is so pronounced that one pole or the other is usually pointed towards the Sun. If you could stand on the north pole of Uranus at the start of its summer, you would see the Sun rise in the sky and circle around for 42 years (1/2 of a Uranian year). Then the Sun would finally dip down below the horizon and be followed by 42 years of winter darkness.

Less Surface Gravity than Earth

Uranus’ density is low at just 1.27 g/cm^{3 –} the second-lowest density of any planet in the Solar System after Saturn.  Despite the fact that Uranus is 14.5 times as massive as the Earth, its significantly lower density means that you would only experience about 89% the force of Earth’s surface gravity, assuming you could stand on Uranus’ cloud tops.

Only been Visited Once

Only the Voyager 2 spacecraft has made a close approach to Uranus. On January 24th, 1986, it passed within 81,000 km of the cloud tops of Uranus and took thousands of photographs of the gas/ice giant and its moons before heading off towards Neptune. The possibility of sending the Cassini spacecraft from Saturn to Uranus was evaluated during a mission extension planning phase in 2009 but never came to fruition, as it would have taken about twenty years for Cassini to get to Uranus from Saturn.

Uranium Namesake

Uranium was discovered in 1789, just eight years after Uranus’ discovery, by the German chemist Martin Heinrich Klaproth.   Klaproth chose to name the new element in honour of the newly discovered planet.

Dark Rings

Uranus has dark coloured rings.   The rings are thought to made up of particles ranging in size from 0.2 to 20 meters that contain a mixture of ices, dust, and debris.  Their discovery in 1977 was serendipitous. Astronomers James L. Elliot, Edward W. Dunham, and Jessica Mink planned to use the occultation of the star SAO 158687 by Uranus to study the planet’s atmosphere. However, when their observations were analyzed, they found that the star disappeared briefly from view five times both before and after it was eclipsed by the planet. They deduced that a system of narrow rings was present.

“Chemistry will get you to Mars, but it won’t get you to the stars.” – Philip Lubin, Astrophysicist at UCSB.

The Planetary Society, NASA, and several aerospace companies are looking to utilize the power of sunlight to sail spacecraft to the stars.

LightSail is a citizen-funded project from The Planetary Society. In 2018, they are launching a small spacecraft on a Space X Falcon Heavy rocket into Earth orbit. Once in orbit, the LightSail 2 spacecraft will be propelled solely by sunlight, aiming to achieve the first controlled solar sail flight in Earth orbit.

LightSail 2 is a three unit cubesat – measuring just 10 x 10 x 30 cm and weighing less than 5 kg. It will deploy a Mylar sail that is roughly the size of two parking spots. The sail captures the momentum of sunlight:  as light reflects off the sail, most of its momentum is transferred, pushing on the sail, and accelerating the spacecraft. Unlike chemical rockets that provide short bursts of trust, solar sails provide a continuous thrust that can result in higher speeds over time.

Tilting the sail steers the spacecraft by changing the angle at which sunlight reflects off it.  The steering technology used in the LightSail 2 demonstration could be used to maneuver cubesats in Earth orbit without fuel. LightSail 2’s performance could also inform NASA’s Near-Earth Asteroid (NEA) Scout solar sail mission which is scheduled to launch in 2019.

Solar sailing is also considered a promising means of interstellar space travel. Last year, the Breakthrough Initiatives announced a plan to send a fleet of small solar sails to Alpha Centauri. An Earth-bound laser array would zap the sails in Earth orbit, accelerating them to 20 percent the speed of light. They would reach the Alpha Centauri system in roughly 20 years and could send back images of the recently-discovered planet Proxima b. One of the first steps is to figure out how to compress a entire spacecraft on to a chip that weighs less than 1 gram.

There has already been some progress on this task. A number of prototype “Sprites” –  fully functional space probes on a single circuit board weighing just 4 grams.– achieved Low Earth Orbit in June, 2017.

 

 

Space weather has the potential to wreak havoc on satellite technologies and cause blackouts. Earlier this month, two large solar flares disrupted radio communication. In March 1989, a similar solar event knocked out power to much of Quebec. Canada intends to study how space weather could impact utility networks, banks, hospitals, and other infrastructure.

Pierre Langlois is part of a team at the Canadian Space Agency looking to understand how space weather could impact the country’s infrastructure. The agency is hiring a contractor to perform a first-of-its-kind study in Canada to assess how its most critical systems, like electrical grids, could be affected by space weather, according to a request for proposals posted on the government’s tenders page.

Space weather refers to the environmental conditions in space and in Earth’s magnetosphere, ionosphere and thermosphere that are due to events that occur on the Sun. Most solar events are associated with sunspots so Canadian scientists at Space Weather Canada monitor sunspots on a daily basis for eruptions such as Solar flares and Coronal Mass Ejectons (CMEs). They provide a space weather forecast that includes Vancouver and the Lower Mainland.

Both solar flares and CMEs involve huge explosions of energy but are otherwise quite different. Flares can last minutes to hours. Most of the energy from solar flares reaches Earth as light. It takes eight minutes for the light from a solar flare to reach us. Some of the energy released in the flare also accelerates very high energy particles that can reach Earth in tens of minutes. The energy from a flare can disrupt the area of the atmosphere through which radio waves travel.

In contrast, CME events hurl solar matter into space. Traveling over a million miles per hour, the hot magnetized particles from a CME take up to three days to reach Earth. The CME particles may interact with Earth’s magnetic fields to produce fantastic displays of northern lights. The magnetic changes can also affect human technologies: High frequency radio waves can be degraded, GPS coordinates stray by a few yards, and electrical currents are created in utility grids.

The new study on the impact of space weather arose out of a recommendation from the United Nations earlier this year. The study has a budget of $300,000 and will take 15 months. The agency wants risk assessments done on the impact space weather could have on a variety of infrastructure systems from road and railway transportation to satellite-based services such as navigation, telecommunication, and military efforts, as well as on government services, banks and hospitals.

Our NOVA Newsletter, for Sept-Oct 2017 is available as a hi-res or low-res pdf file.   An archive of older issues can be found on our Newsletter page.

Contents of Volume 2017, Issue 5, September-October-2017:

• The 2017 Total Eclipse from Madras, OR by Gordon Farrell
• President’s Message by Suzanna Nagy
• A Message from our Observing Chair by Robert Conrad
• Aug 21 Eclipse Event at Science World by Suzanna Nagy
• The Missed Perseids by J. Karl Miller
• RASC’s National Star Party 2017: A Coast to Coast Event by Leigh Cummings

Our public relations coordinator, Scott McGillivray, talked on Global TV about the meteor seen over parts of BC, Cassini’s final days and a chance to see Mercury.

http://globalnews.ca/video/3732563/space-talk-with-scott-12

A team of astronomers, led by Keiichi Ohnaka, of the Universidad Católica del Norte in Chile, used the ESO’s Very Large Telescope Interferometer (VLTI) at the Paranal Observatory in Chile to capture an image of Antares that reveals surface details!  This is the best image of the surface and atmosphere of any star other than the Sun.

Antares is a bright star in Scorpius that shines with a strong red tint.  It is a large red supergiant in the later stage of its life and is expected to become a supernova in a few thousand years.  It is located nearly 620 light-years from Earth with a mass and diameter  of 12 times and 700 times that of our sun, respectively.

The team also made the first map of the velocities of material in the atmosphere of a star, other than the Sun, revealing unexpected turbulence in Antares’s extended atmosphere. In stars like our sun, convection flows of superheated gases bubble up from near the stars’ cores to the surface. But convection cannot explain Antares’ strange atmosphere, and the researchers conclude that, for the atmospheres of red supergiants, there must be another—as yet unknown—process that drives the motion of material.  This process might help explain how stars like Antares lose mass so quickly in the final phase of their evolution.

Ohnaka is hopeful that the observational techniques demonstrated on Antares may be applied to other stars to see how their atmospheres are structured, perhaps revealing the mystery that drives these turbulent motions.

The VLTI consists of up to four telescopes—8.2 m “unit” telescopes and smaller 1.8m “auxiliary” telescopes – that combine light using interferometry to create a “virtual” telescope 200 m wide. Very high angular resolution can therefore be attained, allowing the surface of Antares to be studied in detail.

 

The Royal Astronomical Society of Canada is celebrating Canada’s 150th Birthday with a nation wide star party. RASC Vancouver is holding our event at Maple Ridge’s Selvey Park on Saturday, July 29th, 2017 starting at 08:30 pm.

Our members will have lots of telescopes and binoculars for you to look through, and do not hesitate to bring your own. This is a family friendly event and is free to everyone. Even in July it can get quite chilly at night so please bring clothing layers. Please apply any bug repellent while you are in the parking lot.

This is a weather dependant event and will be cancelled if overcast or raining.

Maple Ridge’s Selvey Park has a relatively dark sky and is less than an hour’s drive from downtown Vancouver.

The light pollution is minimal due to it being surrounded by farm land and people who value the rural life.  This allows viewing of magnitude 5 stars on a moonless night; for example, the dimmest stars in the “Little Dipper” are magnitude 5. If the conditions are good we should get to see a hint of the Milky Way.

The Moon will be 46% illuminated in the evening sky. It will be setting just after midnight so we should have some good deep sky viewing afterwards.

The planets Jupiter and Saturn will also be visible.

The Moon will cover approximately 85% of the Sun in Vancouver during the Solar Eclipse on Monday, August 21st, 2017.  Please join us at Science World where RASC Vancouver will have solar telescopes, solar displays, and eclipse shades for everyone’s enjoyment and safe viewing.  Check out our meetup event or our eclipse page for more information.

 

 

Canada Day 150 is less than one week away so it is good time to respect the colours of flag and do some solar observing in red and white light. At the Canada Day 150 celebrations in Maple Ridge, members of RASC will have telescopes, equipped with red and white filters, available for viewing of the Sun (weather permitting).

Warning: NEVER look directly at the Sun through binoculars, a telescope or with your unaided eye. Serious eye damage and even blindness can result!

High-quality solar filters that remove infrared and ultraviolet radiation and allow only a small fraction of the Sun’s visible light through are required to safely view the Sun. The most popular solar filters are a white light filter where the Sun appears white and a Hydrogen-alpha filter where the Sun appears red.

White Light Solar Filters

White light solar filters are very dark neutral density filters – they transmit only 0.001% of the light. These filters allow you to see sunspots on the surface of the sun and are ideal for viewing solar eclipses and transits of Mercury or Venus. Some granulation (texture) on the surface of the sun can also be seen. However, solar prominences can not be observed with a white light filter and require the use of a hydrogen-alpha filter. Filters made from Baader Astro Solar Film are popular, inexpensive, and high-quality.  Baader solar film is a thin material similar to Mylar that gives a pure white image.

Hydrogen-Alpha Solar Filters

Hydrogen-alpha (H-alpha) filters transmit only one specific wavelength of light: a deep red light that is emitted by the hydrogen atoms which make up the bulk of the sun.  Like white light filters, the overall light transmission is only 0.001% for safe observing, and potentially harmful infrared light is blocked completely.

H-alpha filters are much more expensive than white light filters. The least expensive ones; from companies like Lunt, Coronado, or DayStar; start at about $700.

These companies also offer specialized solar scopes which are normally small refactors with an H-alpha filter already built-in. The sun is bright and does not require a large aperture telescope for viewing it in detail so most solar observers use 40-90mm diameter refractors.

White light filters provide an inexpensive way to start observing the Sun but H-alpha filters reveal its ferocious dynamics. Prominences, spicules, fibrils, and flares become visible. Prominences can be seen at the limb as brilliant blobs, as loops or as sprays. Structural changes can occur in as few as 10 minutes. They’re also capable of shooting higher up in the corona before the material recollects and falls back into the chromosphere.

Images taken through Hydrogen-alpha filters reveal details on the Sun’s surface and can be processed to create a yellow image that is expected by most people.

 

UBC Physicists recently proposed fluctuating space-time in a theory for dark energy that unifies general relativity and quantum mechanics. PhD students Qingdi Wang and Zhen Zhu along with professor Bill Unruh published their research in Physical Review D  last week. You can also find out more by listening to an interview with Jaymie Matthews that aired on CBC Vancouver’s The Early Edition:

The work suggests that, at very small scales, the  universe is constantly fluctuating between expansion and contraction. The fluctuations almost cancel each other but a small net effect is responsible for the “dark energy” that is causing the universe to expand at an accelerating rate.

Previous models of dark energy using quantum mechanics and relativity were not compatible. Models using quantum mechanics theorized that dark energy must be incredibly dense, but relativity predicted that the universe would explode with such dense dark energy.  This new research resolves the incompatibility between the two models.