Big things in May’s night skies

What's happening in Oak Bay's night skies this month

What’s up for May? Two huge solar system highlights – Mercury transits the sun, and Mars is the closest to Earth in 11 years.

Wake up early in Oak Bay Monday, May 9 to see our smallest planet, Mercury, cross the face of the sun. A transit occurs when one astronomical body appears to move across the face of another – as seen from Earth or from a spacecraft.

But be safe – you’ll need to view the Sun and Mercury through a solar filter when looking through a telescope, or when projecting the image of the solar disk onto a safe surface. Look a little south of the sun’s equator. It will take about 7 1/2 hours for the tiny planet’s disk to cross the sun completely.

Since Mercury is so tiny, it will appear as a very small round speck, whether it’s seen through a telescope or projected from a solar filter. It’s really tiny when compared to the larger view we had of Venus transiting the Sun in 2004 and 2012.  Luckily, Mercury transits of the sun occur more frequently than Venus transits do: The next Mercury transit will be Nov. 11, 2019 followed another on Nov. 13, 2032.

The next Venus transit won’t be until Dec. 11, 2117.

Two other May highlights involve Mars.

On Sunday, May 22, Mars opposition occurs. That’s when Mars, Earth and the Sun all line up, with Earth directly in the middle.

Then on Monday, May 30 comes “Mars close approach.” That’s when Mars and Earth are nearest to each other in their orbits around the sun. Mars’ elliptical orbit means the closest approach can occur several days before or after opposition. This year, Mars is over half a million miles closer to Earth at closest approach than at opposition, but is nearly the same diameter and brightness between these two dates.

The last time Mars was this close to Earth was 2005.

As Mars comes closer to Earth in its orbit, it appears larger and brighter. During this time, Mars rises over Mount Baker in the east after the sun sets in the west. The best time to see Mars at its brightest is when it’s highest in the sky – around midnight in May and a little earlier in June.

Through a telescope, you can make out some of the dark features on the planet, some of the lighter features, and sometimes polar ice and dust storms – obscured areas showing little detail.

After close approach, Earth sweeps past Mars quickly, so the planet appears this large and bright for only a couple weeks.

But don’t worry if you miss it. 2018 will be even better, as Mars will be even closer to Earth at its closest approach.

Learn about NASA’s missions to the planets and beyond at www.nasa.gov. Learn more about the RASCals of Cattle Point at facebook.com/groups/VictoriaRASCals/ The group meets at Fairfield Community Centre Mondays at 7:30 p.m.

Dark Skies to all friends of Cattle Point Star Park.

Summary by Bill Smith and the RASCals of Cattle Point is from the transcript of “What’s Up in May 2016” by NASA announcer and astronomer Jane Houston Jones, with permission for localization to Cattle Point DARK SKY Urban Star Park and the Oak Bay News.