Ulysses Patera is a Martian

Mars

Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

 volcano

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

. It is located in the Tharsis quadrangle

Tharsis quadrangle

The Tharsis quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey Astrogeology Research Program. The Tharsis quadrangle is also referred to as MC-9 ....

 at
2.89° north latitude and 121.55° west longitude. It is 58 km across and is named after a classical albedo feature name. Its size changed Sept. 19, 2007 to correspond only to the central depression.

Olympus
is the tallest known volcano. Mons is a term used for a large raised feature. Tholus is about the same, but smaller. A patera is flatter and like a volcano with a super large opening. Actually, a patera was probably formed when the top of a volcano collapsed because its magma chamber was empty. Crater Lake

Crater Lake

Crater Lake is a caldera lake located in the south-central region of the U.S. state of Oregon. It is the main feature of Crater Lake National Park and famous for its deep blue color and water clarity. The lake partly fills a nearly deep caldera that was formed around 7,700 years agoby the...

 Oregon was formed that way.

Tharsis contains many volcanoes, including Olympus Mons

Olympus Mons

Olympus Mons is a large volcanic mountain on the planet Mars. At a height of almost , it is one of the tallest mountains in the Solar System, three times as tall as Mount Everest and more than twice the height of Mauna Kea the tallest mountain on Earth. Olympus Mons is the youngest of the large...

, the tallest known volcano in the solar system

Solar System

The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

.

Ceraunius Tholus

Ceraunius Tholus

Ceraunius Tholus is a volcano on Mars located in the Tharsis quadrangle at 24.2 degrees north latitude and 97.4 degrees west longitude and it is a part of Uranius group of volcanoes. It is 130 km across, 5.5 km high and is named after a classical albedo feature name.It is generally...

 is about as high as Earth's Mount Everest

Mount Everest

Mount Everest is the world's highest mountain, with a peak at above sea level. It is located in the Mahalangur section of the Himalayas. The international boundary runs across the precise summit point...

. Ulysses Patera lies in the southwest.