One of the new habits I’ve taken up during these COVID-19 times is an evening walk around the perimeter of my neighborhood with my wife. We have to do it well after sunset now due to the heat. I enjoy it not only because it’s time set aside for us to talk about the day but also because Jupiter and Saturn are well-situated in the southeastern sky, high enough to be above the nearby homes and trees but not so high to strain my neck.
Besides the moon, Jupiter is the brightest thing you’ll see in the evening sky. The moon will be at full phase tonight, so it’s going to wash out a good-sized chunk of the night sky around it but you should be able to still see Saturn in between the moon and Jupiter.
In nine days for the peak of the Perseids meteor shower on the night of Aug. 11/12, the moon will be a waning crescent phase rising at about 12:30 a.m. Although, more meteors are usually seen after midnight because we’re facing in the direction of the comet dust stream that makes a meteor shower, the moon is going wash out the fainter ones, so observing meteors before midnight is probably the better time. The Perseids have a broad range of activity, so they’re active from mid-July to the second half of August.
Mars is now an evening sky planet, rising shortly before midnight. There are now three spacecraft heading to Mars: the United Arab Emirates’ Hope orbiter launched on July 20, China’s Tiawen-1 orbiter/rover/lander launched on July 23, and the United States’ Perseverance rover was set to launch Thursday. By the time the spacecrafts arrive in February, Mars will be rising at about 11 a.m. in the morning and will set shortly after midnight. After China’s Tiawen-1 arrives at Mars, it’ll spend a couple of months checking things out from orbit before dropping the rover/lander onto the surface.
Campfires on the sun
In other space exploration news, images from the European Space Agency/NASA Solar Orbiter spacecraft during its first close solar pass showed campfires on the sun. “Campfires” is so nice and comforting during these stressful times. In the public relations office, the conversation about the features in the sun’s corona atmosphere may have been something like the following: “Do we call them (a) campfires or (b) mini-flares several hundred kilometers across flickering in the sun’s corona.” “Uh, let’s go with option a.”
Now, something several hundred kilometers across is going to be tiny compared to the sun but scaling the campfires down to Earth scales would be something several kilometers across, which in my experience is called a “forest fire."
These images of the “campfires” are the closest ones yet taken of the sun. Solar Orbiter will get up to two times closer over the next couple of years, so the images will be even more detailed. Solar Orbiter will be providing complementary data with the Parker Solar Probe that was launched in the second half of 2018.
Although the Parker Solar Probe has flown closer to the sun than the Solar Orbiter (and will get even closer over the next few years), Parker does not have cameras because the environment in which it is operating is too harsh for cameras.
Solar Orbiter’s cameras and instruments will complement Parker’s. Solar Orbiter will be changing its path gradually so that it can study the polar regions of the sun, which has only been done once before with the Ulysses spacecraft in the 1990s and early 2000s. However, Ulysses studied the polar regions from a distance at least six times as great as what Solar Orbiter will be able to do.
Eye on exoplanets
Other images from something a bit further away were recently published showing two exoplanets orbiting the star TYC 8998-760-1, which is almost 310 light-years away. This is the first direct image of a multiplanet system orbiting a star with the same mass as the sun. Other multiplanet systems that have been directly imaged are those orbiting stars that are either more massive or less massive than the sun.
Like the other systems, TYC 8998 is very young (only about 16.7 million years old), so the planets are still glowing hot from their formation and the exoplanets are very far from their host star. The exoplanets can be imaged when the star’s light is blocked by a small disk called a coronagraph. Exoplanets far enough away from the star won’t be blocked by the coronagraph.
The closer exoplanet orbits about four times farther out than Pluto orbits the sun. At 14 times the mass of Jupiter, it is probably more like a failed star called a brown dwarf. The farther exoplanet is about six times the mass of Jupiter and orbits at eight Pluto distances from the star. Both exoplanets are way, way outside the habitable zone of the star. The direct imaging of an Earth-like planet in the habitable zone is going to take a large space telescope using a star shade.