Mercury is sliding into the light of dawn this week. Currently about 10° elevation at sunrise, the planet will disappear into the Sun’s glare over the next few days. It will pass through superior conjunction on August 24th, to reappear for an evening apparition around September 8th.
Category: Astronomy
Exploring the cosmos
Postcard from the Universe – Eclipse Viewing
Omega Centauri
New Moon
Perseid Meteor Shower
The Perseids are one of the most watched meteor showers. Occurring during northern hemisphere summer, the shower can be appreciated on a summer night. Quite a difference from the other reliable showers such as the Leonids and Quadrantids, that occur in November and January. Consider a warm summer night under a dark sky full of stars, a picnic blanket, relaxing while shooting stars streak across the sky. What could be better?
The Perseid meteor shower occurs when the Earth passes through a stream of debris along the orbit of Comet Swift-Tuttle. This shower has been consistent throughout recorded history, mentioned in Chinese, Japanese and Korean records as early as the 1st century. Active from July 17th to August 24th, the shower will build slowly for weeks before the peak. A week before or after peak the shower can still be seen with around 20 meteors each hour. The shower is a northern hemisphere event, for southern observers the radiant never rises above the horizon.
The Moon, Mercury, Mars and Jupiter
The dawn is getting crowded. While three planets, Mercury, Mars and Jupiter have been dancing on the dawn stage for weeks now, tomorrow morning a thin crescent, waning Moon will join in. Tomorrow morning the Moon will be 10% illuminated and 4.5° south of Jupiter.
Over the next couple mornings the Moon will continue to wane and slide along the line of planets in the dawn. On the morning of the 4th it will be 5% illuminated and between Mercury and Mars. On the 5th it will be lower than all three and only 1.6% illuminated.
Mercury at Maximum Elongation
Today Mercury reaches maximum elongation, the furthest point it will reach from the Sun in the sky and the highest it will be above the sunrise for this morning apparition. The planet is easily visible as a bright, starlike object about 19° above the rising Sun as the twilight begins. Over the next couple weeks Mercury will slide back into the sunrise, heading for superior conjunction on August 24th.
As Mercury passes through maximum elongation it is part of a trio of bright planets in the morning sky. Higher in the sky you will also see Jupiter and Mars dancing in the dawn.
Postcard from the Summit – Operator’s Station
Southern Delta Aquariids
The Southern Delta Aquariid meteor shower will peak this weekend. This reliable shower usually produces 10-20 meteors per hour. The peak will occur on July 27th this year. As the shower has a broad peak there should still be a good showing a few days either side of peak.
As we are past new Moon there is some dark sky available in the evening, best viewing for this shower is in the morning, when a bright 60% Moon will rise. Moonrise will occur around 22:00HST on the 27th and 22:43 on the 28th. The radiant for this shower will rise at 09:22HST. This provides a slim window of darkness to attempt meteor viewing. After rising, the moonlight will dim the prospects for viewing the shower.
Looking Forward to the Thirty Meter Telescope
While science observations may be almost a decade away, the science possibilities of the Thirty Meter Telescope are already eagerly anticipated by astronomers. In the attempt to answer many of the basic questions of our universe, the limitations of the existing telescopes have become apparent. The eight and ten meter telescopes that represent the forefront of astronomy today are reaching their limit, a limit the research astronomy community is ready to step past.
One thing was clear from the science presentations… The science case for the TMT is compelling. The sheer size of the new telescope will allow observation of the early universe that is just out of reach of the current generation of large telescopes. The thirty meter primary mirror will provide significant advantages even over the next generation of space telescopes in resolution and flexibility of operation. The excellent site available on Mauna Kea allows advantages over the selected site for the European E-ELT in Chile.
While the goal of the conference is to look ahead. It is interesting that what is being presented is a wonderful summary of where current research stands today. In the effort to detail what research could be accomplish with TMT, the astronomers succinctly cataloged the state of current research as it is limited by today’s instruments and telescopes.
Much of the first day discussion was focused on the possibilities of observing the very early universe, the first stars and galaxies that formed in the era just after the big bang. Current telescopes can observe a few tantalizing glimpses of this era, just enough to show astronomers what they do not know about the formation of our universe. A few massive galaxies bright enough to be seen across the gulf of time, a few fainter galaxies that are luckily aligned with closer massive galaxy clusters. Clusters that form gravitational lenses that allow us to peer through a keyhole into the dim past. Astronomer have used every trick they can muster to allow observation of this first era. The TMT will open the door into this first era of stars, allow real study of the beginning of what we see around us today.
Planning for the TMT is in the final stages, where the capabilities of the telescope and the instruments can be forecast with reasonable assurance that those goals will be met. Astronomers can use the design data of the telescope to simulate exposures and signal to noise ratios of the data, on targets they can just barely see today. This sort of planning is critical to the astronomy community, it may be another ten years before science observations begin, but when they do the astronomers will be ready to use the telescope to its fullest capability.
This sort of feedback is critical to the engineers as well. As instruments pass through final development, it is important to know what capabilities are most valuable, what to prioritize when the final design is produced. Questions of spectral resolutions, throughput and exposure times are often heard in the discussions.
Through conferences like this one, the astronomy community will know what to expect when the new telescope comes online around 2022. They will be ready to push forward our understanding of the universe. We know what to expect. But, as Andrea Ghez reminded us, we must “Expect the unexpected!”. Many of the discoveries made by Keck and the other great telescopes of the current generation were completely unexpected. It is likely that the universe still has a few surprises for us.